sorry if this is a very dumb question...

I have just tried four times to send an email to a friend (over a period of about 2 hours). We exchanged emails earlier in the day and everything was fine. But the last four have been returned to me by the Mail Delivery Service saying "bad destination mailbox address".

What's confusing me is that all the returned mail has come back with two attachments. One is the letter I sent, and one is ATT00092.dat (the "092" has been a different number each time). I didn't send any attachments...they were just plain text emails. I sent myself an email to see if the problem was at my end, and received it ok.

I'm not panicking about a virus or anything. I'm guessing it's just that my friend's IP is down or something, but I'm really interested to know what the attachment thing is all about. Like I said...sorry if this is a really dumb question. Sometimes my curiosity gets the better of me.

 

When you have an email returned it is normal to get it as an attachment. I get the same thing.
As far as why it won't send, try clicking on the last one that you received from you friend and click reply and see if it goes ok.