It's the recipients
Most delivery problems to US ISPs boil down to sending mail to people who don’t want it or expect it. Sure, we do technical audits and find issues with how companies are sending mail. But all the technical correctness in the world isn’t going to make up for sending mail users complain about or don’t interact with.
Recently we were working with a client who was having some delivery problems for one mail stream. As we dug down into the issue, we discovered a couple things about the mail stream.
- Addresses were collected by 3rd parties.
- The client sent a welcome series to the recipients.
- More than half of the messages to this list never made it to the inbox.
- Recipients were also invited to join a second list, with similar content.
- Almost all the messages on the second list made it to the inbox.
Given the content and sending setups were nearly identical we can say that the filtering was not about the content. Yes, they were using different IPs and different domain names, but everything else except the recipient population was the same.
Filtering is recipient driven. When you mail to recipients that want your mail, then delivery is generally good. When you mail recipients who don’t care about your mail, then delivery is generally poor.