Senders can be blocked only at the server. Initiating a block from a client is possible when the same firm controls both the server and the client, e.g., Microsoft with Outlook. Thunderbird cannot block. It can only filter. You probably have options at the server for blocking. I block many senders at the server. Blocking and filtering at the server is better if you access mail from more than one client or device.

How does your screen image relate to your inquiry?

Response to a private message:

Thanks for explaining the inability to block an incoming message. Nonetheless, I think there should be another way to actually block received emails more easily than creating a lot of filters. It would seem that a default filter could be applied to an email which is received by a Thunderbird user by some mechanism that each time a new spam email is received, the TBird user could click on that email, and it would simply add that email address to the spam/block list. After the first application to that received address by the User click, the email address would be filtered thereafter without having to be manually clicked by the TBird user. I am not a programmer, but I would strongly expect that this mechanism approach could be created. On a separate issue, I think you might have seen an image which seemed to be applied to the communication by Mozzilla. I sent the question to you by opening the Firefox browser, it was not sent to you by Thunderbird. I can not find the original communication I sent to you, but I do recall that there was some image that seemed to have a very small image related to either Firefox or Mozilla; it also had some very small text. I did not examine either one. If that is the image you are referring to, I did not apply it myself, nor did I examine it before I sent the link to you from Firefox. I am not aware that there was any other image you might be referring to. If so, it would have to be something I did not either insert or see. Thank you again for you response Rick. I will say that I will be investigating an alternative email app that might address the automatic blocking of identified spam.

You can right click on the sender's e-mail address and select "Create filter from" in the drop-down menu. That will filter messages, not block the sender.

Look above for the screen image that you must have posted.

Yes, I understand that you are using Firefox. One must use this forum in a browser window. You cannot send messages to the forum from Thunderbird. You get e-mail messages notifying you of new messages in the discussion. There are two links to the discussion in each notification message. There's no need to use private messages.

As I said, for "automatic blocking", you will need to use webmail or an e-mail client from a firm that controls server and client, e.g., Microsoft. Thunderbird can filter. Now you know a shortcut for creating a filter.