Mail turning up in the wrong mailbox

[#1]

Hi, just a quickie (I hope):
When I started with Plusnet I set up one additional mailbox for the other half. I also set up an alias for each of our mailboxes. I'm finding that, very occasionally, mail addressed to her is coming to me. As far as I can recall it's always her alias that's involved and there is nothing wrong that I can see with the address that's been used. Can anyone suggest where I could start looking for a solution to this?

[#2]

It's easy to get confused if you have received a message because you were specified as a BCC so I wonder if they might be emails sent to both of you. To check this you need to look at the headers/source of the email. Very near the top will be a line "Envelope-to: " which will tell you the email address to which that individual email copy was addressed.

[#3]

Hi jelv, thanks for your reply. I will check that the next time it happens. However I think in all the cases so far these have been messages from websites that my wife has subscribed to (such as estate agents - sound familiar?  ) so it's unlikely they would have been addressed to anyone but her. To the best of my knowledge it's never happened to messages from friends or family.

[#4]

Just a thought
Is your account set as the catchall and is it possible the email address is a bit wrong

[#5]

No, catch-all is off.
The next time it happens I'll take note of the header as jelv suggests and see if that gives any clues.
Thanks.

[#6]

Well, it didn't take long for it to happen again! Once again it's addressed to the alias of my wife's mailbox. The 'envelope to' address in the source is correct. The only thing is that the message has been tagged as -SPAM- so the sender would not have been in her address book. I don't know if that's important.
I've attached the significant part of the source in case anyone can spot anything.
Edit: attachment now removed as issue resolved.

[#7]

What are your settings on the spam tab at http://email.plus.net/, particularly the "How would you like us to deal with messages identified as spam?" setting?

[#8]

Bingo!!
Thanks jelv.