Asking for the impossible: SLAs

English: Pseudoscience troll. Original design.

English: Pseudoscience troll. Original design. (Photo credit: Wikipedia)

Just a few days ago, I wrote that I cannot give a guarantee that an intervention on my part will get you removed from a DNSBL. Why? Because I won’t agree to terms that will bind me to making someone use do something.

I figured that I would follow that up by looking at some contractual terms that your mail consultant and/or ESP will stay away from. Today I would like to have a look at the delivery service level agreement (SLA). A delivery SLA is a contractual term that states that the ESP will guarantee that some percentage of mail will be delivered to recipients. It takes its genesis from the uptime SLAs that ISPs and other providers regularly give to customers doing “mission-critical” things that require that their machines be online and accessible.

Yes, your ESP knows that your ISP is willing to guarantee you 99.9999999999999% uptime. Often, though, companies think that they can get an ESP to guarantee that a certain tremendous percentage of their messages will get delivered. But, remember that your ISP does not guarantee that you can reach a particular website 99.9999999999999% only that their equipment will be up so that you can try. The reasons why you might not be able to reach a website include lots of things that the ISP has no control over, like the website’s system or ISP being down. Similarly, ESPs can only tell you that they will have their systems up to make an attempt, and some do that.

However, an ESP cannot tell you that they will guarantee a certain percentage of email will get delivered. There are too many other things involved to make that kind of promise. Things like:

  • The receiving mail server could be broken and not receiving mail from anyone.
  • An administrator could have typo’d a block/filter string.
  • An undersea cable could have broken meaning that it is impossible for the ESP’s mail server to reach the recipient’s servers on the other side of the ocean.

…And, well, you get the picture. But, perhaps that most important reason is that the ESP generally will have very little control over the message that you are sending. If you, the client, are not careful then your mail stream will suffer from poor delivery as a result of poor reputation. As Laura points out concerning reputation:

ESPs, ISP Relations experts and delivery consultants can guide a sender through the process of repairing reputation. But the only thing that will actually improve reputation is changing sending practices.

If you are not sending mail that people want, then no ESP in the world is going to be able to promise you that your mail will get through.

Stay tuned. Next time, we’ll talk about Inbox Guarantees.


  1. Laura Atkins (2010, May 10), Reputation. Retrieved from

Categories: Industry

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