How to receive only new letters using the POP3 protocol

Question

I use the POP3 protocol to receive my emails in my .NET application. I need to read only new emails, but in many blogs, it is impossible to receive only "invisible" or "new" emails using POP3. It's true? If so, could you help me understand how Outlook Express manages to receive new emails using POP3?

Is there a way so that I can mark the letters I see on the email server itself? Or please help me find out how to get new emails using the POP3 protocol.

Answer 1

You must store UIDLeach email address in a local database. When you want to check new mail, you receive UIDLon the server and see if you have it, if it is already in your local database; if not, this is a new mail.

Outlook uses the same BTW strategy (see this article in KB ).

Answer 2

As long as your mailbox does not store a copy of the letters on the server, then you are in order and should not indicate this.

Typically, when an email client accesses email from the POP3 field, they are downloaded and deleted from the server.

Exchange is a completely different matter.

Greetings