What runs on port 5110

IceWarp Outlook Sync is based on a classical POP3/SMTP account. The SMTP account is set to use an existing IceWarp Server, whilst the POP3 account is set to be inactive. Therefore IceWarp Outlook Sync does not deal with sending emails at all.

However, Outlook itself wants to operate its POP3 account, and Outlook Sync must prevent it from doing so.

For this reason, Outlook Sync is running its own simple POP3 server, bound to 127.0.0.1 and by default on port 5110. IceWarp Outlook Sync listens on this port and simulates zero activity here. Microsoft Outlook connects to this port from time to time and asks for new emails. IceWarp Outlook Sync always answers that there are not any new emails.