Resolved Outlook won't send on 2nd computer

I have Outlook 16.0313029 32bit on two Win 10 Pro computers. Identical installations.

One machine will send mail from my Eastlink POP account
The other machine will not send from the same account in spite of all settings being the same.

The error I get is "Your outgoing SMTP email server has reported an internal error." There is no error code.

I cannot see what the problem might be. Any ideas out there?

Thanks

 

It's the same on both machines. Box is checked.

I tried creating a new profile on the machine that doesn't work and that didn't help.

 

Has it worked previously?
Has anything recently happened to your other comp?

 

the account has worked for well over a year on both computers. Both machines are running the same version of
win 10 Pro
I have changed nothing on either machine

 

I have no solution. It isn't something that is affected by antivirus software or firewall as I have tried with both turned off. This is an intermittent issue as it works some days and not others. Eastlink can not help as they say it is a local issue. Just have to grin and bear it I guess.
Thanks All

 

I would be tempted to do a Reset on the comp that won't Send mail in case there is a problem caused by the updates.