Over at our email accreditation service, SuretyMail, we strongly urge our senders who provision or otherwise host their customers’ outgoing email to give each customer their own outbound IP address.
See, here’s the thing – it’s important to remember that for the vast majority of email sent, the delivery decision is being made on the receiving end by a computer and software. And the first thing that computer and software check when your mail comes a’calling is what ‘hood your email came from, and with whom does it hang in the old ‘hood.
Of course, the ‘hood is your IP address. And the “whom” is what other sorts of email are coming out of that IP address.
If you are providing email services to customers, it doesn’t matter how diligent you are. You may require that your customers build their lists with triple confirmed opt-in with a cherry on top; you are still going to end up having a customer who puts one over on you and slips a dirty list into your system or who, at very least, screws up and, as did one of our sender’s customers, sends to the suppression list instead of, you know, suppressing it. Or, commits some other similar foible which messes up the reputation of the email coming from that IP address.
And when that happens – that customer will have just become the bad guys in the hood, with whom all of your other customers’ email that comes from that same IP address are associated.
Which means that when that one customer gets blocked – when their sending IP address gets blocked, they will just have ruined it for everybody else who sends email from that IP address.
And those other customers of yours will be Very Unhappy.
Unless no other customer is affected, because you’ve given each of your customers their own IP address, and so that one customer didn’t hurt anybody but themselves.
Here’s another reason to give each of your sending customers their own IP address: because when a customer puts one over on you and imports a dirty list, it makes it much easier and cleaner to get rid of them – which translates to making it much easier for us to get your IP space quickly unblocked by all the ISPs and spam filters who are ticked off that your customer spammed their users and so they blocked your IP addresses.
If you absolutely can’t move all of your customers to their own individual IP addresses for some reason, then we recommend that at very least you segregate your IP addresses by mail type and opt-in level, which we’ll talk about tomorrow.