KB1121: Duplicate e-mail notifications ... - Veeam Software
https://www.veeam.com/kb112101.08.2011 · To avoid receiving duplicate e-mail messages, disable the Send e-mail notifications to the following recipients option in the job settings (Backup Destination > Advanced > Notifications). You can also set alternative e-mail addresses in the general Veeam Backup & Replication notification settings ( Tools > Options > E-Mail Settings ).