Never send to old addresses, but what if you have to?

The best practice is to only send mail to people who have specifically asked for your mail, and who have recently interacted with your site.  “Interacted” can mean different things to different people, but generally it means they have logged in to your website, they have recently done business with you, or they have opened or clicked one of your recent emails.  For more, see our best practices document (PDF).

But, what if up to this point you haven’t been tracking those things?  You have a list of addresses that you have acquired over the years, but you don’t have a mechanism in place to know when each one last interacted with you, or perhaps you don’t have a record of how each of those addresses got into your system in the first place.  Maybe you haven’t even been removing addresses that bounce or complain.  Ouch!  This is going to be a problem!

If you just start sending to that list, you have a very high probability of running into problems.  Some of the addresses may no longer be valid, especially if you have not been removing addresses that bounce.  Other recipients may have interacted with you so long ago that they don’t remember you and are now quite likely to mark your messages as spam.  Some old addresses may even have been transformed into spamtraps over the years.  So now it is very probable that you will get flagged for having too high a bounce or complaint rate or even be reported for hitting spamtraps.

You want to be able to improve this situation.

So what do you do?

Before anything else, you need to set up your system to process any bounces and complaints your sending generates, if you aren’t already doing so.  Information on how to do so with SES is here.

You also should set up a mechanism to track both how you acquire new addresses (direct sign up, transactions, etc.) and also when the last interaction with each address happens (open, click, visit, purchase, etc.).  The mechanisms you use for these things are highly dependent on your business and your own use cases, so we won’t get into that in this post, but it is crucial for pruning your list of addresses that are no longer interacting with you.

At this point, the addresses on your mailing list will fall naturally into one of two categories:  addresses for which you have this tracking information (“good addresses”) and addresses where you do not (“questionable addresses”).

Because sending to questionable addresses is highly risky and can possibly generate high bounce and complaint rates, you want to make sure that any such sending is balanced by good sending…  quite a bit of good sending.

We recommend that you send at least 20 messages to “good addresses” for every one you send to a questionable address.  This way, you’re makings sure that the bulk of your sending is to known good addresses that have not bounced, and to recipients you have recently engaged with.  Meanwhile you dribble out a small flow of emails to the questionable addresses.

If sending to these these questionable addresses result in bounces or complaints, remove the addresses from your list immediately and never send to them again.  If your emails are delivered without incident, you can move them into your “good addresses” pool.

Over time, as long as you also purge addresses that have not interacted with you in some time, you will end up with a list that you can feel safe sending to.