ISPs are allowed to bounce your email for any reason, or even no reason at all. We’ve touched on this briefly before, but we think that it’s time to make it crystal clear: ISPs do not have to accept and deliver your email. Or any email. Including, yes, again, YOUR email. Even if your email is double confirmed opt-in with a cherry on top, an ISP is under no obligation to accept or deliver your email.
Of course, if they refused wanted, consented-to email, and for long enough, their users would leave, so they aren’t going to do that. But the point is, if you have ever thought “well, that inbox provider has to accept my email, don’t they?” No, they don’t. In fact, CAN-SPAM very specifically leaves email delivery decisions up to the individual ISPs and inbox providers, and exempts them from legal liability for those decisions.
Whether you feel that it’s right or wrong is immaterial: it’s how it is.
So ranting and raving about how “people want your email”, or how it’s not spam so the ISPs “should” deliver it, will get you nowhere. Or, more to the point, it will get your email nowhere. Like it or not, your email is a guest at the ISP. You wouldn’t expect to be welcome if you pounded on someone’s door and demanded to be let in, would you? In the same way, your email will be much more welcome, and likely to get where you want it, if you use email manners.
In a way you can think of the email certification and deliverability services like us as charm school for your email. :-)
The very best email etiquette includes both making sure that you have the consent of the person whose email address you want to put on your mailing list before you put it on your mailing list and securing the confirmation of that consent (i.e. confirmed opt-in). But at the very least making sure that you have consent before you put that email address on your mailing list.
That email etiquette also includes making sure that there is an easy, clear way for someone to opt out of your email in every single mailing list email that you send to them. Of course, the law requires that you include an opt-out method, but some people try to make it hard to find, thinking that will reduce unsubscribes; and while they may be technically right that it will reduce unsubscribes, that’s because it increases spam complaints. This is not a polite way to provide an unsubscribe link; the good email etiquette way is to make it really easy for people to unsubscribe if they want to. Ironically, the easier you make it for people to unsubscribe, the less they will want to.
Anyways, all of this to say: practice good email etiquette, and make it so that people want and welcome your email, and then their inbox providers and ISPs will want to accept and deliver your email. If you don’t, and they don’t, well, that’s a choice they get to make. It’s the law.