Can you correctly answer these 6 questions on the origins and history of American Thanksgiving?

We are only what we are in the dark; all the rest is reputation. What God looks at is what we are in the dark—the imaginations of our minds; the thoughts of our heart; the habits of our bodies; these are the things that mark us in God’s sight.

• The Love of God—The Ministry of the Unnoticed, 669 L

By whom the world is crucified unto me, and I unto the world. — Galatians 6:14

If I brood on the Cross of Christ, I do not become a subjective pietist, interested in my own whiteness; I become dominantly concentrated on Jesus Christ’s interests. Our Lord was not a recluse nor an ascetic, He did not cut Himself off from society, but He was inwardly disconnected all the time. He was not aloof, but He lived in an other world. He was so much in the ordinary world that the religious people of His day called Him a glutton and a winebibber. Our Lord never allowed anything to interfere with His consecration of spiritual energy.

The counterfeit of consecration is the conscious cutting off of things with the idea of storing spiritual power for use later on, but that is a hopeless mistake. The Spirit of God has spoiled the sin of a great many, yet there is no emancipation, no fullness in their lives. The kind of religious life we see abroad to-day is entirely different from the robust holiness of the life of Jesus Christ. “I pray not that Thou shouldest take them out of the world, but that Thou shouldest keep them from the evil.” We are to be in the world but not of it; to be disconnected fundamentally, not externally.

We must never allow anything to interfere with the consecration of our spiritual energy. Consecration is our part, sanctification is God’s part; and we have deliberately to determine to be interested only in that in which God is interested.

Station Idents and Interval Signals

Lilliburlero

Trumpet Voluntary

Above: Used for many years on the BBC World Service (formerly the General Overseas Service) before news bulletins Lilliburlero is a traditional Irish tune.

Above right: The European Service signature tune, the Trumpet Voluntary. Attributed to Purcell on the label, but now generally thought to be by Jeremiah Clarke.

Right: The Call Sign for the Pacific, Eastern, Colonial and North American Services. The original recording dates from 1948

blackhawk887 Ars Tribunus Angusticlavius
9y
19,694
100% TNT equivalent is crazy. Even 25% is probably twice a reasonable figure. The FAA uses 14% for LOX/hydrogen and 10% for LOX/kerosene. Hydrogen is more than twice as energetic per mass of methane, and kerosene about 80% as energetic as methane.

LOX and liquid methane are miscible, unlike the other combinations, but there aren't any plausible scenarios where you'd get better mixing than a rocket falling back on the pad shortly after liftoff, which both kerolox and hydrolox are also perfectly capable of doing. //

mattlindn Ars Centurion
7y
231
NASA's current blast range evacuation area ranges from 3 to 4 miles as shown in the diagrams in this article (I measured it on google maps).

It's worth mentioning that the privately run Rocket Ranch down in South Texas where people can pay money to get closer to the Starship launches is only 3.9 miles from the launch site. The people who watch from the Mexico can get as close as 2.4 miles.

Where most people (including myself) watch(ed) from, South Padre Island, is almost exactly 5 miles away.

So yeah this seems kind of excessive. //

Jack56 Ars Scholae Palatinae
7y
672
For the nth time, a fuel-oxidiser explosion is not a detonation. It is a deflagration. They are far less violent. An intimate mixture of gaseous oxygen and methane can detonate but liquid methane and liquid oxygen cannot mix intimately - are not miscible - because methane is a solid at lox temperatures, especially the sub-cooled lox which Starship uses. A detonation takes place in under a millisecond. Deflagrations are fires. I’m not saying it wouldn’t be bad but comparisons with an energetically equivalent mass of TNT are way out of line. //

mattlindn Ars Centurion
7y
231
Jack56 said:

For the nth time, a fuel-oxidiser explosion is not a detonation. It is a deflagration. They are far less violent. An intimate mixture of gaseous oxygen and methane can detonate ....

Didn't think about this, but yes you're correct. The boiling point of Oxygen is 90.2 K and the melting point of Methane is 90.7 K. If you mix the two together, before any Methane can melt all the oxygen has to boil off. Though there should still be some local melting given the outside air temperatures are MUCH warmer than the liquid oxygen.

Though at the same time given the temperatures are so close together I don't think much Methane will freeze before an explosion happens. So maybe the point is moot? //

SpikeTheHobbitMage Ars Scholae Palatinae
3y
1,745
Person_Man said:

I have to imagine a fully fueled stack with optimal mixing for the biggest explosion would probably be the largest non nuclear explosion ever.

Most of Starship's propellant is oxygen. The full stack only carries 1030t of methane (330t on Ship, 700t on SuperHeavy). Methane also has a TNT equivalent of only 0.16. Using the omnicaluclator, I get 1030t of methane* = 164.8t of TNT. That doesn't even make the top 10 list.

*omnicalculator lists natural gas, which is mostly methane. //

blackhawk887 Ars Tribunus Angusticlavius
9y
19,694
mattlindn said:

Didn't think about this, but yes you're correct. The boiling point of Oxygen is 90.2 K and the melting point of Methane is 90.7 K. If you mix the two together, ...

Mixing with oxygen should depress the freezing point of methane. For example, if you take water at its freezing point, and mix it equally with alcohol that is itself, say, 10 degrees colder than the freezing point of water, the resulting mix will be well below 0 C but will not contain any frozen water.

Also, you can mix butane and water under a little pressure, even though at atmospheric pressure butane boils a half-degree below the freezing point of water. They aren't miscible, but that's just because of polarity - they are happy to both be liquids at the same temperature and a little pressure.

Methane and LOX are considered miscible and were even considered for monopropellants at various mix ratios. The mixture is reportedly a bit shock sensitive though. //

SpikeTheHobbitMage Ars Scholae Palatinae
3y
1,745

Mad Klingon said:
For the many debating using eminent domain to expand launch facilities, that would likely be the simple part of the issue. Most of that area is considered sensitive wildlife area and dealing with the current piles environmental regulations and paperwork could take decades for a major expansion. Look at all the grief SpaceX gets when they build on the relatively bland bit of Texas coast they are currently using. It would be much worse at the Florida site.

One of the great legacies of Apollo was we got a well built out area for launching stuff before most of the environmental legislation was passed.

One of the great legacies of Apollo was that the exclusion zone around Cape Canaveral preserved enough of the wetlands in good enough condition to become a protected nature reserve.

“Until we get that data from the testing that is ongoing and the analysis that needs to occur, we’re going to continue to treat any LOX-methane vehicle with 100 percent TNT blast equivalency, and have a maximized keep-out zone, simply from a public safety perspective,” Chatman said.

The data so far shows promising results. “We do expect that BDA to shrink,” he said. “We expect that to shrink based on some of the initial testing that has been done and the initial data reviews that have been done.”

That’s imperative, not just for Starship’s neighbors at the Cape Canaveral spaceport, but for SpaceX itself. The company forecasts a future in which it will launch Starships more often than the Falcon 9, requiring near-continuous operations at multiple launch pads. //

The Commercial Space Federation, a lobbying group, submitted written testimony to Congress in 2023 arguing the government should be using “existing industry data” to inform its understanding of the explosive potential of methane and liquid oxygen. That data, the federation said, suggests the government should set its TNT blast equivalency to no greater than 25 percent, a change that would greatly reduce the size of keep-out zones around launch pads. The organization’s members include prominent methane users SpaceX, Blue Origin, Relativity Space, and Stoke Space, all of which have launch sites at Cape Canaveral.

The government’s methalox testing plans were expected to cost at least $80 million, according to the Commercial Space Federation.

The concern among engineers is that liquid oxygen and methane are highly miscible, meaning they mix together easily, raising the risk of a “condensed phase detonation” with “significantly higher overpressures” than rockets with liquid hydrogen or kerosene fuels. Small-scale mixtures of liquid oxygen and liquified natural gas have “shown a broad detonable range with yields greater than that of TNT,” NASA wrote in 2023. //

SpaceX said it has conducted sub-scale methalox detonation tests “in close collaboration with NASA,” while also gathering data from full-scale Starship tests in Starbase, Texas, including information from test flights and from recent ground test failures. //

The company did not disclose the yield calculation, but it shared maps showing its proposed clear areas around the future Starship launch sites at Cape Canaveral and Kennedy Space Center. They are significantly smaller than the clear areas originally envisioned by the Space Force and NASA, but SpaceX says it uses “actual test data on explosive yield and include a conservative factor of safety.” //

Concerns as mundane as traffic jams are now enough of a factor to consider using automated scanners at vehicle inspection points and potentially adding a dedicated lane for slow-moving transporters carrying rocket boosters from one place to another across the launch base, according to Chatman. This is becoming more important as SpaceX, and now Blue Origin, routinely shuttle their reusable rockets from place to place. //

Space Force officials largely attribute the steep climb in launch rates at Cape Canaveral to the launch industry’s embrace of automated self-destruct mechanisms. These pyrotechnic devices have largely replaced manual flight termination systems, which require ground support from a larger team of range safety engineers, including radar operators and flight control officers with the authority to send a destruct command to the rocket if it flies off course. Now, that is all done autonomously on most US launch vehicles.

The Space Force mandated that launch companies using military spaceports switch to autonomous safety systems by October 1 2025, but military officials issued waivers for human-in-the-loop destruct devices to continue flying on United Launch Alliance’s Atlas V rocket, NASA’s Space Launch System, and the US Navy’s ballistic missile fleet. That means those launches will be more labor-intensive for the Space Force, but the Atlas V is nearing retirement, and the SLS and the Navy only occasionally appear on the Cape Canaveral launch schedule.

It's impossible to guarantee a long timeframe because of entropy (also called death!). Digital data decay and dies, just like any other thing in the universe. But it can be slowed down.

There's currently no fail-proof and scientifically proven way to guarantee 30+ years of cold data archival. Some projects are aiming to do that, like the Rosetta Disks project of the Long Now museum, although they are still very costly and with a low data density (about 50 MB).

In the meantime, you can use scientifically proven resilient optical mediums for cold storage like Blu-ray Discs HTL type like Panasonic's, or archival grade DVD+R like Verbatim Gold Archival, and keep them in air-tight boxes in a soft spot (avoid high temperature) and out of the light.

Also be REDUNDANT: Make multiple copies of your data (at least 4), and compute hashes to check regularly that everything is alright, and every few years you should rewrite your data on new disks. Also, use a lot of error correcting codes, they will allow you to repair your corrupted data!
Long answer

Why are data corrupted with time? The answer lies in one word: entropy. This is one of the primary and unavoidable force of the universe, which makes systems become less and less ordered in time. Data corruption is exactly that: a disorder in bits order. So in other words, the Universe hates your data. //

Long-Term Archival

Even with the best currently available technologies, digital data can only be cold stored for a few decades (about 20 years). Thus, in the long run, you cannot just rely on cold storage: you need to setup a methodology for your data archiving process to ensure that your data can be retrieved in the future (even with technological changes), and that you minimize the risks of losing your data. In other words, you need to become the digital curator of your data, repairing corruptions when they happen and recreate new copies when needed.

There's no foolproof rules, but here are a few established curating strategies, and in particular a magical tool that will make your job easier:

Purge Old SpiderOak files

SpiderOak keeps an unlimited number of previous versions. This doesn't cause a problem in most cases, but can be an issue for files that change frequently, particularly if you backup multiple times a day or if the files don't compress very well. So I've created a batch file to handle this for you. You do not need to run it often, but maybe once or twice a year it can save you a lot of space.

The file takes a while to run, more time when more needs to be deleted, so be patient. It will keep the daily backups copies for 10 days, weekly for 10 weeks, monthly for 12 months and one a year thereafter. This should be more than enough for most purposes. Clicking on the batch file will close SpiderOak, open a command console, delete the historical file, update the history records, restart SpiderOak and close the command console. I have it reporting everything it does, so you can watch if you like.

The text file I've also posted will explain the 6 lines of the batch file in case you want to adjust the parameters I've chosen, or see how it works.

RALPH WILLIAMS
Business as Usual, During Alterations
Throughout most of recorded history mankind has lived within an economy of scarcity. Only in the last half-century have technological developments made an economy of abundance possible, at least in the West and Japan. The costs involved in this process were high, not only in terms of human exploitation but also in more subtle ways. For example, the explosion of available consumer goods has produced considerable confusion, part of the "future shock" phenomenon of being surrounded by so much diversity that it is difficult to enjoy any of it.

Because technological change has been so rapid, entire industries have been created and wiped out almost overnight. The resourcefulness often shown by the businessman to these
developments has been little short of amazing-the transition from a literally "horse-powered" transportation system to the automobile and from the blacksmith to the mechanic are but
examples.

"Business as Usual, During Alterations" presents members of the business community facing the greatest crisis in the history of economic relationships. Competition is supposed to be the essence of the Free Enterprise System (at least on paper)-but it was never supposed to be like this.

Mike Woodruff has been a pastor for over 40 years. During that time, an increasing number of people have been captured by conspiracy theories, overwhelmed with anxiety or seething in anger. 5 years ago, Mike embarked on a journey to understand what was happening.

He discovered the primary forces reshaping the news and the necessary practices for staying sane in a 24/7 news cycle. On The News will explain what’s happened since the Cronkite era and then offer a pathway for you to navigate this strange new world.

George shook his head slowly. "You're wrong, John. Not back to where we were. This morning, we had an economy of scarcity. Tonight, we have an economy of abundance. This morning, we had a money economy—it was a money economy, even if credit was important. Tonight, it's a credit economy, one hundred per cent. This morning, you and the lieutenant were selling standardization. Tonight, it's diversity.

"The whole framework of our society is flipped upside down.'" He frowned uncertainly.

"And yet, you're right too, it doesn't seem make much difference, it is still the same old rat race. I don't understand it."

-- BUSINESS AS USUAL, DURING ALTERATIONS by Ralph Williams (Astounding Science Fiction, 1958)

I bought a box of SF pulps when I was in my late teens from one of my father's friends, who kept them in the garage. English editions of Astounding Science Fiction, for the most part. Stories written by authors whose names I barely recognised, despite being a science fiction reader from about as soon as I could read.

I paid more than I could afford for them.

I suspect that one story paid for all of them, though.

It's a thought experiment. I'd forgotten the opening of the story (aliens decide to Mess With Us) but remembered what happened after that.

We're in a department store. And someone drops off two matter duplicators. They have pans. You put something in pan one, press a button, its exact duplicate appears in pan two.

We spend a day in the department store as they sell everything they have as cheaply as possible, duplicating things with the matter duplicator, making what they can on each sale, and using cheques and credit cards, not cash (you can now perfectly duplicate cash – which obviously is no longer legal tender). Towards the end they stop and take stock of the new world waiting for them and realise that all the rules have changed, but craftsmen and engineers are more necessary than ever.

That companies won't be manufacturing millions of identical things, but they'll need to make hundreds, perhaps thousands, of slightly different things, that their stores will be showrooms for things, that stockrooms will be history. That there will now be fundamental changes including, in 1950s-style retailing, in a phrase that turned up well after 1958, a long tail.

Being Astounding Science Fiction, the story contains the moral of 95% of Astounding Science Fiction stories, which could perhaps be reduced to: people are smart. We'll cope.

When my friends who were musicians first started complaining sadly about people stealing their music on Napster, back in the 1990s, I told them about the story of the duplicator machines. (I could not remember the name of the story or the author. It was not until I agreed to write this introduction I asked a friend, via email, and found myself, a google later, re-reading it for the first time in decades.) //

I remembered what Charles Dickens did, a hundred and fifty years before, when copyright laws meant that his copyrights were worth nothing in the US: he was widely read, but he was not making any money from it. So he took the piracy as advertising, and toured the US in theatres, reading from his books. He made money, and he saw America. //

Fortunately, Cory Doctorow has written this book. It's filled with wisdom and with thought experiments and with things that will mess with your mind. Cory once came up with an analogy while we argued that explained the world that we were heading into in terms of mammals versus dandelions to me, and I've never seen anything quite the same way since.

Mammals, he said, and I paraphrase here and do not put it as well as Cory did, invest a great deal of time and energy in their young, in the pregnancy, in raising them. Dandelions just let their seeds go to the wind, and do not mourn the seeds that do not make it. Until now, creating intellectual content for payment has been a mammalian idea. Now it's time for creators to accept that we are becoming dandelions.

The world is not ending. Not if, as Astounding Science Fiction used to suggest, humans are bright enough to think our way out the problems we think ourselves into.

I suspect that the next generation to come along will puzzle over our agonies, much as I puzzled over the death of the Victorian Music Halls as a child, and much as I felt sorry for the performers who had only needed thirteen minutes of material in their whole life, and who did their thirteen minutes in town after town until the day that television came along and killed it all.

In the meanwhile, it's business as usual, during alterations.

-Neil Gaiman

martinusher

Re: Having Equity Makes a Big Difference!
"Pie in the sky", I believe its called.

(From an old song by Joe Hill, "The Preacher and the Slave"....

You will eat, bye and bye,

In that glorious land above the sky;

Work and pray, live on hay,

You'll get pie in the sky when you die.

BTW -- "Its a lie!")

“This is an absolutely massive story of foreign ops shaping our political and cultural discourse,” Dave Rubin wrote. “Will the set of influencers who fell for it look in the mirror?”

It’s ironic, of course, that the 2016 screams of “foreign influence” on the Trump campaign have now been replaced by actual evidence of foreign influence — mostly aimed against Trump.

But there’s a bigger story here.

The United States, for all its size and power, is prone to the whims of public opinion — and its communications are largely open to outsiders.

It’s hardly surprising that some of those outsiders will seek to take advantage of our nation’s freedom of expression.

For many years, and continuing today, that external influence has been manifested in foundations, grants, donations, lobbying and — hello, Biden family! — outright bribes.

If you can redirect a multitrillion-dollar government by spending a few million on campaign contributions or “consulting” contracts, that’s a pretty good deal.

But fake X accounts are even easier, and even cheaper.

It costs virtually nothing for a malign operator to set up accounts, farm engagement and accumulate enough followers to be — or at least to seem — influential.

Causes that are not actually popular can be made to look like they have genuine momentum behind them, even if that “momentum” is just a few nerds pecking keyboards in Third World countries.

And X is an ideal outlet for this scam because lazy journalists — and there are a lot of those — often rely on it for easy-peasy cut-and-paste clickbait stories. //

But Musk on Friday didn’t censor people for lying. He revealed them as liars.

Rather than repression, he chose illumination.

“Know the truth, and the truth will set you free,” as it says in the New Testament.

Or perhaps, in the words of Supreme Court Justice Louis Brandeis, “Sunlight is said to be the best of disinfectants.”

Musk chose transparency over “security,” and in so doing he ripped the masks off tens (hundreds?) of thousands of fake accounts that have been doing real harm to America’s political discourse — without silencing anyone.

Jet A and Jet A-1 are kerosene-type fuels. The primary difference between the two is freeze point, the temperature at which wax crystals disappear in a laboratory test.

Jet A, which is mainly used in the United States, must have a freeze point of minus 40ºC or below and does not typically contain static dissipator additive. Jet A-1 must have a freeze point of minus 47ºC or below and for locations outside the United States, this fuel normally contains static dissipator additive. There are other key differences between the manufacturing specification within the United States and Europe/Africa/Middle East/Australasia.

The emergence of synthetic pigments in the 19th century had an immense impact on the art world, particularly the availability of emerald-green pigments, prized for their intense brilliance by such masters as Paul Cézanne, Edvard Munch, Vincent van Gogh, and Claude Monet. The downside was that these pigments often degraded over time, resulting in cracks and uneven surfaces and the formation of dark copper oxides—even the release of arsenic compounds.

Naturally, it’s a major concern for conservationists of such masterpieces. So it should be welcome news that European researchers have used synchrotron radiation and various other analytical tools to determine whether light and/or humidity are the culprits behind that degradation and how, specifically, it occurs, according to a paper published in the journal Science Advances. //

The results: In the mockups, light and humidity trigger different degradation pathways in emerald-green paints. Humidity results in the formation of arsenolite, making the paint brittle and prone to flaking. Light dulls the color by causing trivalent arsenic already in the pigment to oxidize into pentavalent compounds, forming a thin white layer on the surface. Those findings are consistent with the analyzed samples taken from The Intrigue, confirming the degradation is due to photo-oxidation. Light, it turns out, is the greatest threat to that particular painting, and possibly other masterpieces from the same period.

Gen7 (N54L, N40L, N36L)
The N40L comes with 1 × 2GB ECC RAM installed. It will accept up to 16GB (2 × 8GB) 240-Pin DDR3 SDRAM 1333 (PC3 10600) RAM [1]

Non-ECC RAM is compatible, but not recommended for mission critical servers. Most casual, NAS or home server systems do not require ECC RAM.[2]

Does not support registered (buffered) modules. Using registered modules will result in the server failing to POST/boot. ('blue light').

Capable of utilizing dual channel RAM, which results in marginally increased memory speeds when two matched DIMMs are installed.[3]

Eclipse tables in the Dresden Codex were based on lunar tables and adjusted for slippage over time. //

The Maya used three primary calendars: a count of days, known as the Long Count; a 260-day astrological calendar called the Tzolk’in; and a 365-day year called the Haab’. Previous scholars have speculated on how awe-inspiring solar or lunar eclipses must have seemed to the Maya, but our understanding of their astronomical knowledge is limited. Most Maya books were burned by Spanish conquistadors and Catholic priests. Only four hieroglyphic codices survive: the Dresden Codex, the Madrid Codex, the Paris Codex, and the Grolier Codex. //

They concluded that the codex’s eclipse tables evolved from a more general table of successive lunar months. The length of a 405-month lunar cycle (11,960 days) aligned much better with a 260-day calendar (46 x 260 =11,960) than with solar or lunar eclipse cycles. This suggests that the Maya daykeepers figured out that 405 new moons almost always came out equivalent to 46 260-day periods, knowledge the Maya used to accurately predict the dates of full and new moons over 405 successive lunar dates.

The daykeepers also realized that solar eclipses seemed to recur on or near the same day in their 260-day calendar and, over time, figured out how to predict days on which a solar eclipse might occur locally. “An eclipse happens only on a new moon,” said Lowry. “The fact that it has to be a new moon means that if you can accurately predict a new moon, you can accurately predict a one-in-seven chance of an eclipse. That’s why it makes sense that the Maya are revising lunar predicting models to have an accurate eclipse, because they don’t have to predict where the moon is relative to the ecliptic.” //

“The traditional interpretation was that you run through the table, eclipse by eclipse, and then you rebuilt the table every iteration,” said Lowry. “We figured out that if you do that, you’re going to miss the eclipses, and we know they didn’t. They made internal adjustments. We think they’d restart the table midway. When you do that, you go from having missed eclipses to having none. You would never miss an eclipse. So it’s not a calculated predictive table, it’s a calculated predictive table plus adjustments based on empirical observations over time.”

“This is the basis of true science, empirically collected, constant revision of expectations, built into a system of understanding planetary bodies, so that you can predict when something happens,” said Lowry.

A simple proposal on a 1982 electronic bulletin board helped sarcasm flourish online. //

The emoticons spread quickly across ARPAnet, the precursor to the modern Internet, reaching other universities and research labs. By November 10, 1982—less than two months later—Carnegie Mellon researcher James Morris began introducing the smiley emoticon concept to colleagues at Xerox PARC, complete with a growing list of variations. What started as an internal Carnegie Mellon convention over time became a standard feature of online communication, often simplified without the hyphen nose to :) or :(, among many other variations. //

Between 2001 and 2002, Mike Jones, a former Carnegie Mellon researcher then working at Microsoft, sponsored what Fahlman calls a “digital archaeology” project. Jeff Baird and the Carnegie Mellon facilities staff undertook a painstaking effort: locating backup tapes from 1982, finding working tape drives that could read the obsolete media, decoding old file formats, and searching for the actual posts. The team recovered the thread, revealing not just Fahlman’s famous post but the entire three-day community discussion that led to it.

The recovered messages, which you can read here, show how collaboratively the emoticon was developed—not a lone genius moment but an ongoing conversation proposing, refining, and building on the group’s ideas. Fahlman had no idea his synthesis would become a fundamental part of how humans express themselves in digital text, but neither did Swartz, who first suggested marking jokes, or the Gandalf VAX users who were already using their own smile symbols. //

Others, including teletype operators and private correspondents, may have used similar symbols before 1982, perhaps even as far back as 1648. Author Vladimir Nabokov suggested before 1982 that “there should exist a special typographical sign for a smile.” And the original IBM PC included a dedicated smiley character as early as 1981 (perhaps that should be considered the first emoji).

What made Fahlman’s contribution significant wasn’t absolute originality but rather proposing the right solution at the right time in the right context. From there, the smiley could spread across the emerging global computer network, and no one would ever misunderstand a joke online again. :-)

SPF "breaks" email forwarding. SRS is a way to fix it. SRS is a simple way for forwarding MTAs to rewrite the sender address.

For a mail transfer agent (MTA), the Sender Rewriting Scheme (SRS) is a scheme for rewriting the envelope sender address of an email message, in view of remailing it. In this context, remailing is a kind of email forwarding. SRS was devised in order to forward email without breaking the Sender Policy Framework (SPF)

In my previous post Custom Domain E-mails With Postfix And Gmail: The Missing Tutorial, we set up a Postfix mail server on a custom domain that integrates seamlessly with Gmail.

However, the tutorial skipped two important security standards that will help prevent e-mails routed through our server from being marked as spam: DKIM and SRS. This article will show you how to add support for DKIM and SRS to a Postfix server. //

DKIM, short for DomainKeys Identified Mail, is a mechanism for

1. A sender e-mail program to sign an outgoing e-mail message, and
2. A recipient e-mail program to verify said signature.

SRS, short for Sender Rewriting Scheme, is a standard for including forwarding / relay information in a forwarded / relayed e-mail message.