| ASRG | Anti-Spam Research Group | PRA | Purported Responsible Address Sender ID |
| BATV | Bounce Address Tag Validation | SPF | Sender Policy Framework |
| DKIM | DomainKeys Identified Mail | SRS | Sender Rewriting Scheme |
| DSN | Delivery Status Notification bounce | SMTP | Simple Mail Transfer Protocol |
| MARID | MTA Authorization Records In DNS | SMTP AUTH ESMTPA authentication | |
| PGP | Pretty Good Privacy | S/MIME | Secure / MIME |