Hello @vschafer,
All Weekly activity reports are sent from the server where your website is based at and From name: Security Optimizer by SiteGround.
The subject is always Subject: Weekly Activity for YourWebsiteName
This is set by default in the plugin’s configuration and the only way to be modified is if the email is forwarded or there is a custom setting within the recipient’s mail.
More information and full details on the configuration can be found under /wp-content/plugins/sg-security/core/Activity_Log/Activity_Log_Weekly_Emails.php
Best regards,
Georgi Ganchev
SiteGround.com