How difficult is it to get on whitelists?

Today’s question comes from Leslie J.

Just how difficult is it for a small business that runs a highly compliant mailing system to find
their way onto whitelists at the big freemail/spam filter providers?

It seems utterly impossible meaning man hours are completely wasted messing around with subjects and content when if the same business sends the very same message through any number of well know ESPs, the message will hit the inbox like the Mafia are in charge of the shooting match.

There are a couple questions wrapped up in this email.

One is that most of the freemail / spam filter providers don’t offer whitelisting any longer. The two that do offer whitelisting (AOL and Yahoo!) whitelist by IP address not by content. The delivery problems from self hosted mail could be any number of things, some of which you the sender can control and some of which the sender can’t.

I’ve helped clients troubleshoot delivery problems in these situations and seen a couple different reasons why there was a problem with the mail.

  1. The sender did not do any warmup on the IP address and decided to switch to an ESP before the IP reputation had a chance to develop. Had they warmed up the IP or just waited for a little while longer, the delivery problems would resolve themselves.
  2. The sender was using an open source MTA (sendmail, postfix, qmail) or Exchange to send the mail. These MTAs don’t have the controls bulk mail systems need. For instance, qmail will open up dozens or hundreds of connections at a time. This type of behaviour creates a negative reputation.
  3. There is a configuration problem with the sending MTA that triggers spam filters because the mail looks like it’s coming from spam ware.
  4. The sender is actually using a shared mail server provided by their hosting company, and the IP reputation is poor because of other traffic going through the server.

Most of these issues are resolved by going to an ESP. The ESP will have clients on fixed IPs do a proper warmup. Most ISPs use software designed to give them the level of control over mail sending that leads to a good reputation. ESPs know how to configure a sending machine to not look like spam ware. The better ESPs keep track of customers and don’t let poor customers ruin delivery for other customers.

There are also a couple other things ESPs do behind the scenes that can improve delivery.

  1. ESPs have finely tuned bounce handling, that prevents excessive mailings to non existent email addresses.
  2. ESPs won’t send to known traps, role accounts and other bad addresses. This means there is less of a chance to develop a bad reputation.
  3. ESPs correct bad content (non ASCII characters, too long line lengths, etc) minimizing the problems caused by invalid content.
  4. ESPs know how to configure machines to not look like spam ware.

Any one of these things could explain the different success between mailing off a business IP address and mailing through an ESP.

It’s not a given, though, that the only way to get to the inbox is to mail through an ESP. A number of my clients are small mailers who are mailing through their own MTAs. Our standard audit identifies and offers corrections for configuration issues and content problems. We also provide advice on warmup, bounce handling and will process FBL signups for clients. Many clients going through our audit program discover that their mail reaches the inbox without having to use an ESP or pay for certification.


Have a question you want me to answer? Tweet them to @wise_laura or send them to


  1. Challenge of the Week: The Myth of Whitelisting | E-mail Marketing Specialisten says

    [...] sending wanted mail to the right people (only). Over on the Word to the Wise blog, Laura Atkins talks more about what underlying problems typically actually need to be fixed, when somebody asks, "how do I [...]

  2. Chris says

    In the real world, ESP’s send to traps a lot too & get blocked poor delivery too. Many of them care about a 250 port 25 delivery as opposed to inbox vs spam folder delivery.
    Good ESP’s send to traps less and have low complaint rates because they only send mail people want & engage with. Anyway, I agree that fixed IP is the only option & monitoring the situation & managing the reputation of that IP is why you pay the ESP. They already have feedback in place, which is ideal for the lazy marketoids.

    Conversely, this also explains why ESP’s with multi tenant IP’s are completely screwed. (The same goes for shared hosting too…) 1 crap list import and it’s goodbye Vienna. The proof of the pudding recently has been political mail, where complaint rates were so high they have little hope of not hitting the spam folder.


  3. John says

    Can you elaborate on specifics of “configure machines to not look like spam ware”?

  4. laura says

    Hi, John,

    That’s a good question and I’ll answer it on Wednesday.


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