Programming POP3 Protocol (Outlook Express 5)

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Hi,

One of our members writes:
” need some help with programming the POP3 protocol. I have the basics working fine (listing and receiving messages and deleting them off the server), but I notice that OE5 can POP3 messages and leave a copy on the server, and then know enough not to receive those messages a second time. Who knows how that is done? I have POPped messages out of an account with OE5 and then ran my radio e-mail program, but it still pulls those messages out. I thought it might be doing a TOP command to read through the message header to find some “already read” flag, but I tried that and couldn’t find any information in the header that would indicate to me that I shouldn’t read this message again. I’m looking at the 1996 POP3 protocol standard; is there something more recent that has some magic commands?”

TIA for your assistance.

Bob Wahlen

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Off the top of my head I don’t know the command for not removing the email off of the server. In fact, I thought that it was a direct command TO delete the email from the server. When you list the emails, you should be sending an email ‘id’ through. That is what OE is using to determine if it has gotten that email before. On an exchange server, a message’s ID is a 255 character key, so it allows for an impossibly immense number of emails to be stored before it would have to reuse a ‘key’.

So OE determines what’s been read or not (it keeps track), not the server.

Drew

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Outlook Express 5.x uses a file named pop3uidl.dbx to track downloaded messages.

See: Microsoft Knowledge Base Article 216366 – OLEXP: How to Download Internet Mail Messages in Outlook Express Multiple Times
See also: Microsoft Knowledge Base Article 314578 – OLEXP: You Receive Duplicate Messages When You Download E-Mail from the Server in Outlook Express

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