When you click Test Config Postie tries to connect your your mail server to ensure everything is set up correctly. (Be sure to click Save first if you changed anything!). Unfortunately sometimes the error messages aren’t very clear and you need a way to verify things.
One common issue is that the port you are trying to use is blocked or your mail server isn’t listening on the port. You can verify these conditions by using the telnet command.
Note: You need shell access to the server Postie is installed on.
Connect to your server via RDP, VNC or SSH and open a command/terminal window and type something like the following:
telnet mail.examples.com 110
Substitute the server and port you are trying to verify. If successful you should see something like:
Type ‘Q’ and press return to tell the mail server you’re done.
For a IMAP (port 143) you should get something like:
Type ‘C logout’ and press return to tell the mail server you’re done.
For POP3-SSL or IMAP-SSL you need to use a different command. For example to test if you can get access to Gmail IMAP try:
echo "TAG LOGOUT" | openssl s_client -connect imap.gmail.com:993
For Gmail POP-SSL try:
echo quit | openssl s_client -connect pop.gmail.com:995