Canon scan to email broken after PaperCut installation

We have a number of Canon copier/printers at various sites. Up until last week, scan to email was working fine at one site but after installing Paper Cut for Follow Me printing at one site, that site can no longer scan to email. The Scan to email settings haven't changed and scan to email at other sites (not yet converted to Paper Cut) is still OK.

Canon **iR ADV C5850** machines at all sites.

Comparing the SMTP settings from a working site to the "broken" site show all the same settings for server, email address, SMTP TX (587), Allow TLS is set. The 365 account associated with scan to email is mailbox enabled. Clicking the "Check connection" button results in a "Connection was successful" message at the Paper Cut and non-Paper Cut sites. Yes attempting to scan to email at the PaperCut site results in a Converting, Sending, resending until it fails with an 801 error (timeout while sending to SMTP).

The ONLY thing that is different between the working and non-working sites, is that the non-working site has Paper Cut app installed on the printer.

Not sure who to engage, PaperCut or Canon (or both). Very reluctant to move forward with PaperCut implementation without resolving the scan to email issue **first.**

Thoughts, anyone??