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Tag: SMTP

Does email have a guarantee of delivery?

A client asked me earlier this week what SLAs ISPs provided for email delivery. The short answer is that there isn’t a SLA and that the only guarantee is that the email will get there when it gets there. But as I was mentioning this to Steve, he pointed out that there was a recent […]

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8 things that make your mail look like spam

In the comments of last week’s Wednesday question John B. asked Can you elaborate on specifics of “configure machines to not look like spam ware”? There are a lot of things that spamware does that is different from a lot of standard MTAs. Here are a list of things that may make your mail look […]

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The Physics of the Email Universe

We talk a lot about rules and best practices in email, but we’re mostly talking about “squishy” rules-of-thumb that are based on simplified models of how mail systems, spam filters, recipients, postmasters and blacklist operators behave. They’re the biology, ecology and sociology of the email ecosystem. There’s another set of rules we tend to only […]

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Email is store and forward

Many of us are so used to email appearing instantaneous, we forget that the underlying protocol was never designed for instant messaging. When the SMTP protocol was originally proposed it was designed to support servers that may have had intermittent connectivity. The protocol allowed for email to be spooled to disk and then sent when […]

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  • ReturnPath on DMARC+Yahoo

    Over at ReturnPath Christine has an excellent non-technical summary of the DMARC+Yahoo situation, along with some solid recommendations for what actions you might take to avoid the operational problems it can cause.No Comments


  • AOL problems

    Lots of people are reporting ongoing (RTR:GE) messages from AOL today.  This indicates the AOL mail servers are having problems and can't accept mail. This has nothing to do with spam, filtering or malicious email. This is simply their servers aren't functioning as well as they should be and so AOL can't accept all the mail thrown at them. These types of blocks resolve themselves. 1 Comment


  • Fixing discussion lists to work with new Yahoo policy

    Al has some really good advice on how to fix discussion lists to work with the new Yahoo policy. One thing I would add is the suggestion to actually check dmarc records before assuming policy. This will not only mean you're not having to rewrite things that don't need to be rewritten, but it will also mean you won't be caught flat footed if (when?) other free mail providers start publishing p=reject.No Comments


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