Reader George Tweedy wrote to ask about getting multiple copies of large emails:
Terry, Why is it that I sometimes receive multiple copies of emails download at the same time? It seems to happen more with large files such as pictures and movie clips. Deleting them only brings back a new batch of the same mail.
I wrote back to George to tell him that the first thing to check is whether they are actually multiple sendings of the emails or multiple copies being created during the email sending & receiving process.
You can tell if they were sent as multiple copies by looking at the message headers in the email. There is one line in the message headers that starts with
followed by a long string of alpha-numeric characters.
If you’ve actually received multiple copies of the same message because of problems when downloading, the Message-ID will be the same.
So, how can you get multiple copies that have the same Message-ID?
When you download emails, your email program sends an acknowledgement (and ACK) to the sending mailserver to indicate that the email was received successfully.
If you’ve got noise on your phone line (if you’ve got dialup or DSL) or on your cable system Internet service, you might receive the file successfully, but the ACK may not be sent successfully. So, the mailserver sends it again.
Another issue would be if you disconnected while you were still downloading emails. When your email program is set to delete emals after downloading – that’s exactly what it does – it deletes them after it receives ALL of them. If you disconnect too early, the emails are at the mailserver to be downloaded again the next time you connect.