Mail gets delivered as many times as its recipients

Try a self test email and add CC or few more recipeints to this test email.
Make sure there are no problematic rules on the client side.
Check delegation on affected user's outlook/client.
If user is using any hand held device like blackberry or anything, that also could be an issue.

In PopCon are you POP downloading as a catchall account or individual accounts?  How do you have the delivery configured in the POP3 page in PopCon?

Also, check which Headers you have PopCon configured to process.  Should be on the Advanced Tab.  Maybe you need to remove some of them.

Its using one pop3 catch all account. We have it working on many sites without ever having a problem but this one user keeps getting multiple mails where the other people on the server dont?

That's strange.
Can you make some test to see if there is any type of mail forwarding at the Exchange side?  Is there any correlation to the other addresses in the email.

Like send a test message to him and 1 other recipient.  Then test using some other person as the extra recipient (someone unrelated to the user), etc..

It only seems to happen when all the receipients are all the same email address endings i.e. matt@microsoft.com, alex@microsoft.com etc It doesnt happen if the cc is a different domain

You mean if its sent 4 time TO Somebody AT the domain that your downloading for the pop3?

Well thats how you would expect a cathall to happen!  If i sent an email to John@ Paul@ fred@ Steve@  and none of them existed then the catchall account would have 4 emails waiting to download.

I don't follow with the CC comment.

Let's say Joe@company.com is getting the duplicate messages.

Example of the Email message:  TO:  joe@company.com      CC: mary@company.com , smith@company.com, jones@company.com

If that email is received, then joe only gets 4 copies when the other people are exactly those 3 people?  or it seems that way?

Can you make a test email and see the results.
mail1:  TO: joe        CC:    mary , smith  and put youself in the CC list

mail2:   TO:  joe      CC:  put yourself in the CC

How is the result on that?

Apologies:

If the email gets sent to matt@example.com, alex@example.com, mary@example.com then matt@ gets it 3 times

If the email gets sent to matt@example.com, alex@microsoft.com he only gets it once

What about just to matt and mary?  multiple copies received by matt , is any forwarding type of setting on mary's account.

You could look at the popcon log and maybe see something there?  Those logs don't have too much detail though.  I am using an older 3.5x version, maybe a newer version has more options.

Just to Mary and Matt gets two. The settings have no forwarding on them and i cant see a setting in Popcon. There are more settings in Popcon for AV and Spam but if you dont enable these at install they dissapear from the settings window. But seems odd as they would more likely block than send twice

How about the popcon log file.  Normally it should show some brief info like
mail from xya@123.com delivered/forwarded to matt, mary, etc..

when the log entry shows up is there a duplicate (like it shows 2 times).
If not then I would look at the Exchange side and Mary's Outlook.  Maybe they setup a forwarder at some point and don't remember?

You might also think about turnnig on the SMTP logging at exchange then search the emails to matt and see what is shown on the Exchange side (example.  if you send a test message with expected duplicates  to both matt and mary, then you should be able to spot the log entries and maybe you see 2 connections from POPcon or something to shed light on what is going on).

Cant resolve why and its only one mailbox so have given up

Solved problem