So, ive just spent the morning going through a whole host of things with Google and also testing the settings that @Keith Stevenson Pointed out.
We still have errors and are unable to send.
In google we disabled 2factor on the account in question. Tried signing in with the username and password but it was rejected as we werent using an application password, so we tried with the application password with 2fa enabled, this also failed.
This brought us on to this @Steve Giller https://support.google.com/accounts/answer/6010255?authuser=4&p=less-secure-apps
Whilst this doesn't immediately affect us it soon will.
Google are discontinuing their support for less secure applications in May, which meant we lookgin into enabling OAuth for sending, only to find out that using your Google Connector you can only connect to calendars as Hornbill is not verified with Google.
If I click Advanced and Continue I can only share the Calendar with Google.
and cos of this its not viisble within the OAth Settings of Send Mail.
So currently STILL as it stands we cannot send emails and its causing no amount of issues, just by changing a password
We declined as customer success call as we were more than happy with Hornbill but currently Im inclined to have a conversation just to raise this issue.
@Keith Stevenson You were correct in forming me that it will test once, to which this does and successfully sends the email, but doesnt send on the scheduled sender.