Explanation of port numbers and encryption methods.

Question

Андрей Михалевский 3,451

Hello. I have Exchange 2019 on-premise.

I tried to connect ThunderBird mail client via IMAP protocol.

I don't understand what protocols and encryption methods are needed.

Can you explain in detail about ports and encryption methods ?

Should I use only 25 and STARTTLS as modern technologies ? I have heard that ports 465\587 are considered obsolete.

I can't relate, ports, encryption methods and how the connectors in Exchange depend on it.

Mike Hu-MSFT 4,145 Reputation points Microsoft External Staff

2024-07-01T01:17:35.0366667+00:00

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Mike Hu-MSFT 4,145 Reputation points Microsoft External Staff

2024-07-01T01:17:35.0366667+00:00

If an answer has been helpful, please consider accepting the answer to help increase visibility of this question for other members of the Microsoft Q&A community. If not, please let us know what is still needed in the comments so the question can be answered. Thank you for helping to improve Microsoft Q&A!

Answer 1

Andy David - MVP 157.8K

Hi, you can follow this:

Use port 993 for IMAPs for the client to retrieve mail

port 587 to send mail:

Андрей Михалевский 3,451 Reputation points

2024-06-27T08:07:37.9433333+00:00

Hi. Why 993 ? TLS more prefer, then ssl. And i can't connect to 587 port. Can only 25. But telnet listen 587.
Andy David - MVP 157.8K Reputation points

2024-06-27T11:02:59.25+00:00

993 is the encrypted port for IMAP client access to retrieve mail.

If you can only port 25 to send mail, then thats ok as well.