An old bug that was present in V7 has returned in V9.1 almost immediately after updating.
When sending an email to someone, a second blank email without subject is sent simultaneously to the same people and with with all the recipients of the previous mail in BCC.
This happens randomly on a small percentage of sent emails and only on eM Client. Outlook, Thunderbird and other email clients are unaffected, making it extremely unlikely for this to be a server-side problem.
We have 10 licenses and, so far, it has happened to everyone who has updated to 9.1
Mail server is Gmail (Professional / Google One)
This didn’t happen throughout the entire V8 generation of eM Client
Obviously, this annoys our clients who receive random blank emails from us.
EDIT: running version 9.1.2109 (9967b93)