Facebook Messenger does not have a specific tool

or feature to let you know if someone has blocked you.

You can infer that you have been blocked

by checking on a few things,

but these do not guarantee

that you have indeed been blocked.

Looking at how the Messenger app behaves

when you send a message may give you clues

that you have been blocked.

When you use the Messenger app on your phone

or in a browser,

you may be familiar with the status icons

next to the messages you send.

There are four such icons.

An unfilled empty circle

means the message has not been sent.

This is typically because you don't have

any internet access when you try to send a message.

An unfilled icon with a check mark

means the message has been sent,

but not delivered to the recipient.

A check-mark icon that's filled in

means the message has been delivered.

An icon that's filled in

with the recipient's profile picture

means it has been read.

If the recipient is logged on to Facebook,

your message should be delivered within a few moments,

and you will see the check-mark icon.

Once the recipient views your message,

the icon will change to the message-read status

with the profile image.

If you send a message to someone

and the message is not delivered,

meaning that only an unfilled check-mark icon appears,

it generally means one of two things:

The user has not logged in to Facebook,

or the user has blocked you on Messenger.

It's not always possible to tell the difference,

but if you see that the recipient has posted

to their Facebook page

or comments on other people's posts,

that implies that they're logged in to Facebook.

If your message remains undelivered,

you're probably blocked.