No, you cannot tell if someone has blocked your email or your texts. That’s also true for most instant messaging tools like Facebook Messenger, Snapchat, WhatsApp, and others.
When there’s no feedback, there’s just no way to know what happened.
Let’s explore why I say that.
Many reasons, mostly spam
The root problem is there are many reasons your mail or texts may not get through. It’s usually related to managing spam and occasionally due to misconfigurations.
If you don’t get any message back indicating why something failed, it’s basically impossible to determine which reason applies.
It could even be a combination of reasons.
You could be blocked by your recipient
It’s possible your intended recipient has indeed blocked you. All this means is email from your email address or texts from your mobile number will be automatically deleted or immediately filtered to spam. In most cases, that’s all a “block” really is.
You may not get any kind of notification.1
All you can do is ask the recipient to make sure they haven’t blocked you, assuming you have some other way to contact them.
If they respond, and it turns out they have blocked you, you can ask them to explain their reasons for blocking you in the first place (pay attention to those reasons), and ask them to unblock you.
You could be blocked by your recipient’s ESP
It’s possible your email address has been blocked by the recipient’s email service provider (ESP), or by a spam filter along the way.
These days it’s pretty rare, but it’s still a possibility. If your email address has been seen as a source of spam at any point in its history (for example, if your account has been hacked and used to send spam), then sometimes ESPs will block it. Mobile providers may have similar lists for mobile numbers known to have sent text-messaging spam.
If you get no bounce message in return, there’s really no way to know if your email has been blocked and discarded.
Your ESP could have a bad reputation
The reputation of your email service provider plays a large role in determining whether your messages will be delivered.
If your email service has a reputation of being the source of a lot of spam — meaning it allows its services to be used by spammers — then all email originating from that service suffers.
Fortunately, most hard blocks of this type do generate a bounce message with some indication of the problem. However, just as with you being individually blocked, if you get no bounce message in return, there’s really no way to know whether your ESP has been blocked.
Your message could look “spammy”
More often than being blocked, email is instead often discarded or diverted into a spam folder because it “looks spammy”. Exactly what that means varies quite a bit and constantly changes.
Worse, there are no absolutes, and everything combines. The spammy-ness of your message, plus the reputation of your ESP, plus the history of your recipient’s use of the “this is spam” button, and more all combine at delivery time to determine what happens to your message.
I’ll assume your message isn’t attempting to promote body-part enhancement products or other common spam topics. Even so, it might make sense to review your message with the eyes of a spam filter in mind.
If your email gets filtered as spam, you get no notification.
Things to try
If you find your email has been filtered into your recipient’s spam folder, make sure they mark it as “not spam”. This trains the spam filter that you’re not a spammer. It may take marking multiple messages to do this.2
You might also ask them to look into allow-listing your email address on their service, if they have that ability, or allow-listing your mobile number, if this is a text messaging issue. (Allow-listing identifies known email addresses or phone numbers and allows them through.)
Another test would be to send using a different provider, beginning with simple test messages that are unlikely to be flagged as spam due to their content.
The bottom line, however, is that if someone explicitly blocks you, there’s really no way to know unless they also explicitly tell you.
Footnotes & References
1: If you do, of course, examine it carefully for clues as to why your message was not delivered.
2: As in many messages. And, depending on the spam filter being used, it may not work at all.
Leo Notenboom has been programming computers since 1976, and answering questions about them online since 2003. For more, see askleo.com.