Return path
The hidden address that bounces go back to, separate from the From address people see. SPF is checked against its domain.
How this affects you
Every Vaartix domain's return path is vxmail.yourdomain (or vx-bounces.yourdomain on older domains, and when vxmail already receives email). Gmail shows it as "mailed-by" under "Show details". It has to be a subdomain: Amazon SES requires it, and an MX record on your main domain would take over its inbox. Until its MX and SPF records pass, email still goes out, but shows "mailed-by amazonses.com".
Learn more
Vaartix is a transactional email API built in India. SPF, DKIM and a return path on your domain are set up for you, and every feature is free during the private beta.