Why can't AfterLogic Webmail connect to the mail server?

Question

linux

Hello! Such a question: I set up a mail server on a VPS with Debian 8.5 according to this instruction . Additionally, I installed the Afterlogic Webmail web mail client.
When trying to authorize, it gives a message:
An error occurred while trying to connect to the mail server.
What could be the reason?

Answer 1

php -m show.
Check if the php-imap module is enabled

Answer 2

Turn on the Afterlogic Webmail logs ( afterlogic.org/docs/webmail-lite/troubleshooting/d... ) and see what happens there.
Afterlogic Webmail does not use php-imap, it has its own implementation of the protocol.