That is very strange. Any addition info you can give? Were those members somehow connected? (friends, mailed each other before...)

I have also came across this sometimes ago.

I am not sure Aliia it seems to be happening to everyone but I am not sure if  people are getting email because of a connection of friendship or not I know I get emails as well that I should not get but I have the admin pal and I am friends with everyone so it would be hard to say for me I do know I recently set up a smtp server and my tech has checked over everything and has confirmed it is oxwall script sending the emails to the wrong people

Joseph, I have registered a couple of users on your site ( I have PMed you their usernames). Let's see if I will be able to reproduce the issue ( might take some time).
Let me know if you yourself notice anything that might help us.

I havent noticed anything that could help however I was thinking try adding a few friends and lets see if you receive emails about them that you shouldnt like private messages between them and another person