Someone wanted to add me and i accidently denied him/her. Because that window appeared right beneath my mouse as i was about to click on something else. I had no time to see what the mail was like.
I hope u understand what i mean.
Yes it does happen. Tools>Options>Security then you will find the e-mails you have blocked or denied in the block list, right click on the one you have accidently denied and click Move to allow list.