The port 993/TCP… is used by…IMAPS To allow a client to view a TLS protected IMAP mailbox. It concerns the access to messages, not their transport between servers; its diagnosis must therefore distinguish between connectivity, TLS negotiation and authentication to the messaging service…
What is the purpose of Port 993?….
The port 993/TCP… is used for…IMAPS, i.e. IMAP with implicit TLS: TLS negotiation takes place immediately before opening the connection before IMAP commands. It serves clients who view and synchronize messages while maintaining folders on the server. It differs from port 143, whereTLS can be used according to configuration…
Transport Protocol
TCP
Safety precautions
Should we open this port in the firewall?
An Internet exposure of 993 can be normal when a mail service must be accessible to the customers of the Service. However, it must be voluntary: TLS properly validated, methods of authentication adapted, monitoring attempts and deactivation of,IMAP for accounts which do not need it…. Do not replace a certificate problem with a deactivation of its validation….
How do I check this port?
Check first the tactile with…. Test-NetConnection SERVER -Port 993, then go to service with…. openssl s_client -connect SERVER:993 -servername SERVER. Once TLS is validated, analyze separately the methods of authentication and the status of the box…
- Control DNS and accessibility to the game….
- Check certificate, chain and name presented…
- Ensure that the server allows IMAP for the account….
- Read d logs, authentication if the TLS session works but login fails….
FAQ — port 993 / IMAPS….
What difference between ports 143 and 993?….
993 uses TLS implicit from the moment of connection. On 143, IMAP can start in plain and then use ▼TLS according to the server configuration…
Why 993 is open but the account doesn’t connect?…
The network can work while the account’s certificate, the authentication, license or the IMAP activation blocks the session….
Can port 993 be published on the Internet?….
Yes if the IMAP service is to be remotely accessible and the courier security policy provides for it, then it must be properly protected and monitored.