| API key | Credential used to authenticate Mailtarget API or SMTP requests. |
| Bounce | Delivery failure reported by a receiving server. |
| DKIM | Signature mechanism that proves a message was authorized by the sending domain. |
| DMARC | Policy layer for domain alignment and authentication failures. |
| SPF | DNS record that authorizes sending infrastructure. |
| Suppression | A recipient state that prevents future sends. |
| Tracking domain | CNAME used for click and open tracking links. |
| Transmission | A submitted email request and its delivery lifecycle. |
| Webhook | HTTP callback sent by Mailtarget when message events occur. |