Publishing ports for IMAP

Question

Hi. I have:

rl-edge.domain.com 10.10.10.1 - edge server
mail.domain.com - 10.10.10.2 mailbox server

Exchange 2019 one-premise.

I have port forwarding on my router.

25 port to rl-edge.domain.com and 443 port to mail.domain.com

I need to connect from the outside world via IMAP. What ports should I forward and where?
587 and 993 to rl-edge.domain.com ? Will it proxy to mail.domain.com ? Should I use 587 instead of 25 ? What is the difference ?

Do I have to configure anything else besides turning on services?

Answer 1

Use 587 for SMTP, as that is the client submittal SMTP port used for authentication.
Enable and start the IMAP services if they are not already.

Follow this guide:
https://learn.microsoft.com/en-us/exchange/clients/pop3-and-imap4/configure-imap4?view=exchserver-2019

For the cert, it will use the existing 3rd party cert which are using for mail.domain.com