Mail delivery failed via SMTP server 'None'



I’m trying to give Flectra a test drive today on a fresh Ubuntu 18.04 install. I’ve set SMTP and POP incoming/outgoing servers based on Zoho’s recommendations.

First I had to apply a custom fix I found online as Zoho does not support relay, I have included a screenshot below.

After this fix was implemented, I still cannot send email and am given the error “Mail delivery failed via SMTP server ‘None’.”.

This issue did not occur yesterday while we were still using Odoo 10 (with the same fix in place for relay).

Does anyone have any idea what would cause this and how I could fix it? The account used for pop/smtp already has catchall/bounce aliases.