Blocking a player removes the mail from the mailbox, but still shows the "new messages" indicator ball for the mails from that player.

And yes I've actually blocked one player for spamming. Every game I've been playing with him/her on the same match that player is sending -wanna-join-my-corp- message BS.

The player in question was not nor has ever been in my contact list. Whether (s)he has me in his/her contact list I don't know. I added him/her on my blocked list due to the spam e-mails. I've received several messages from this player all of them having only message topic "join-in-my-corp" or something like that and no message body. The first time I received this I replied him thanking for the offer, but declined as I'm happy with my current corporation.

Once (s)he was blocked I still got the orange dot indicator for "unread mail" on social . Removing the block brought "unread messages" from the blocked sender my mailbox and they could be read normally.

I'm not talking about the notifications although the issue might also manifest there as you very well demonstrate in the video. Since I added the block and removed it to check if those "unread mails" were from that player and then enforced it again I haven't observed being in the same battles as (s)he and hence I believe (s)he hasn't been sending me new messages since, but I'll report back in when this happens again.

The bug itself is minor, but annoying as the orange dot wont go away unless you unblock the sender and "read" the messages.

Edit: Just another thought. It might have been that the messages were in mailbox as unread when I blocked that player and still showed the orange "unread mail" indicator once the block was enforced.