If you are still having issues, you will need to follow Option 2 on this link. The 75xx series does not support TLS 1.2
Sounds like you have tried everything already, so it would be a software escalation: 1-800-821-2797 or 1-800-835-6100.
Is anyone aware of why the scan to email isn't working for this serie anymore through Office365?
I have tried to FW upgrade for the latest SPAR release 062.121.001.24900 without any luck.
Is it because of the SHA-2 and TLS 1.2 tenant upgrade from Office365, or am I missing something in the configuration? I have doubled checked the SMTP Authentication, the from address, IP configuration etc.
I have also tried to disable/enable the NTLM option from the hidden side.
Any help would be appreciated.