Follow up to this, ive not had much help from Grandstream other than telling me to change passwords use GMAIL and is the RAM full? (6208 with 30 phones running for 2 days with no voicemail, i would hope the ram isnt full).
However the reason for this thread was to work out what would be in the packet capture, i just ran another and did the same test and i DO SEE SMTP packets this time, so this confirmed the UCM didnt even attempt to send the email on the LAN when it appeared to not be sending emails, it actually didnt even attempted to send them, we rebooted the UCM and its now working.
I know this has been an issue before, has anything ever gotten to the real source of the issue with this?
This UCM is in client mode. Ive had similar issue with SFTP when an SSL certificate changed, it gives up as well without trying, so is there an SSL certificate caching issue in the UCM?