UIDValidity value between sessions

Question

Hello,

We have some problems with a Lotus Domino IMAP server which returns different UIDValidity values for the same message between sessions. This means that if I connect and list messages from today, it could return UIDValidity 5. When I disconnect and connect immediately again and list messages, now the UIDValidity is 6. I have single message in inbox.

Do you have any idea how to track whether I already processed that message or not ? Obviously, I can't store "User name/Mailbox name/UID/UIDValidity/Server name" information in order to mark which messages are already processed, because the same message produces different information next time I connect to that server.

Answer 1

Do you have any idea how to track whether I already processed that message or not?

If the server is changing folder's UIDVALIDITY every time you log in there is not much you can do.

For sure you can't rely on message UID to identify specific message.

You can use:

• flags (\SEEN \UNSEEN use Imap.Search(Flag.Unseen))
• custom flags (if your server supports that)
• use separate folder/subfolder for processed messages and move each message after processing: Imap.MoveByUID (https://www.limilabs.com/blog/move-emails-to-different-folder-with-imap)
• message-id header (not very efficient)

I must say that such server behavior is very strange and I think you should consult your administrator and ask him why the server is acting this way. The problem may be with failover configuration, maybe always connecting to the specific machine would solve that.