Time is System > Admin Menu > System Settings > Clock Settings
As for the why it is because the printer typically is set to HTTPs, which brings in SSL Clock Synchronization.
Without knowing the server requirements I can't go into Encryption abilities. I believe the printer in question does not support SSL or TLS, which pretty much leaves you stuck with using a relay since almost everything uses SSL/TLS/STARTTLS.
If you were trying to use gmail for instance it would be impossible on smtp.gmail.com as it requires TLS on port 587, or SSL on port 465.
In that case you would have to use the un-authenticated SMTP server which is aspmx.l.google.com as it uses port 25, no encryption and no authentication, but then you are limited to sending to only gmail and google accounts email addresses as it cannot do SMTP relays.
Office 365 also does that
Smtp server: [domain].mail.eo.outlook.com
Outgoing port: 25
No encryption, no authentication.
Example:
Xerox.com is my domain which would make the server Xerox-com.mail.eo.outlook.com
Beyond that you would need a wireshark trace to diagnose further as all I can do here is guess since I have no line of site to your setup.