Yes, on 7.03.
When I reactivated the plugin it started sending the last few bits of my message from a few days ago.
The site reported this error:
An error of type E_ERROR was caused in line 58 of the file /home/naf/public_html/wp-content/plugins/acymailing/back/helpers/global/curl.php. Error message: Maximum execution time of 300 seconds exceeded
I will increase the execution time to see if that helps.