Members PM is sent to webmaster
 

I have no idea what's happen.
But some "standard" members private message is being e-mailed to the webmasters address to. Almost like if they has entered the webmasters address as there own address, but that's not the case. All of them has there own address.

do you have any plugin/hack related to private messaging, or emails ?!

The only hack/add-on we have is Image Resizer and Is Bot: Registration Time Check.
No one of them has anything to do with PM or mail.
I dont know, but could someone in the webmaster crew change any settings somewhere that should not be changed?

Have to bump this one up since i still have the same problem, but i'm also know what's causing the problem.

If a member send a PM to another member, that has enabled "mail me if i recive a PM" function, but also has a old or non functional e-mail. The "Undelivered mail returned to sender" mail are sent to webmasters e-mail instead.
Any way to stop this?

Bump

Bump again sice the problem still occurs

Sounds like the PM system has a CC of Admin. When Receiving a pm from a regular member, what does it show? Like a quoted message? Direct message? Are the PMs being sent to the required recipient?

Thanks for fast answer.
What do you mean with?
I've contacted some of the senders, and all of them has just quoted the PM and sent back to the first sender.

When you recieve a "normal" mail it looks like this.

Subject
You have recieved a new private message from xxx forum

Text
Hi "nickname"
You have recieved a new private message at xxx forum from nickname, with title "xxxxxxx"

Exact the same mail are dropping in at the webmaster e-mail to. Not all the time, but way to much

Are you sure they are not 'bounce' notices due to a bad email address?

By CC it means it sends a copy of the mail to the webmaster (or admin). I'd make sure the email address the users have provided are legit, otherwise it won't send emails but it would, seem like, send the webmaster an email to notify the email address is incorrect.