We have enhanced synchronization working for the clients on the same network as the Mitel 5000. I am now trying to get it working for some users who are on another network (and another e-mail server). I've filled out the e-mail sync page with the correct server name, username, password, etc. IMAP port 143 is open on both firewalls. The closest I'm getting is the Mitel will in fact deliver the voicemail to the recipient's inbox. But it's not synchronizing once the user has marked the mail as read or deleted it. The phone still flashes the message light and the display shows there is one new message.
The recipient's email server only has a self-signed cert on it. That is why I am using synchronization with SSL turned off (port 143). Is SSL for E-mail Server Connection required to get this to work fully? And does that require a third-party cert?