In my incoming mail settings activity screen, I'm seeing one of these warnings every 10-15th message. All the other messages import with no problem. What do these warnings mean?
Could not retrieve headers for that messsage. Does message with id #1 exists?
Could Not Connect To Mailbox: SECURITY PROBLEM: insecure server advertised AUTH=PLAIN, Mailbox is empty, SECURITY PROBLEM: insecure server advertised AUTH=PLAIN, Can not authenticate to IMAP server: [CLOSED] IMAP connection broken (authenticate)
1) "Could not retrieve headers for that messsage. Does message with id #1 exists?"
You should not be worried about it. This is minor glitch. Sometimes the number of new emails in inbox is changed during importing of emails, so activeCollab tries to download non-existing message, and because of that it returns that error. This issue will be addressed, so you won't see this error.
2) "SECURITY PROBLEM: insecure server advertised AUTH=PLAIN". I cannot tell you for sure why are you seeing this error. Which POP/IMAP server do you use? Dovecot maybe? Are you trying to connect to SSL secured server while using TLS, or NO security option.
Could not retrieve headers for that messsage. Does message with id #1 exists?
Could Not Connect To Mailbox: SECURITY PROBLEM: insecure server advertised AUTH=PLAIN, Mailbox is empty, SECURITY PROBLEM: insecure server advertised AUTH=PLAIN, Can not authenticate to IMAP server: [CLOSED] IMAP connection broken (authenticate)