If error in email address, sending to rest of the recipients is stopped with smtp error [#2925509]

I use Mass Contact + Ultimate Cron + SMTP

When sending a message with or without pdf attachment.

My sending list is interrupted after a e-mail recipients who has an error in the e-mail adress, (in my case that email recipients no longer exist.)

There after all other following recipients in the sending list got same SMTP-error message in log, saying "Invalid address". Nothing more.

I have been checking the problem directly with web-hotel.
Drupal do not send any mail to the SMTP - mail server after the first recipient with the e-mail error.
All recipients before the recipients, who has the error in email address, Is send and these recipients receive the e-mail message.

Please advice if any solution to this problem
This problem look a bit like this: https://www.drupal.org/project/smtp/issues/2358001