Using the Deliverability Assessment Tool

Because most spam doesn't actually originate from the address it claims to be coming from, many ISPs and email providers have started to implement authentication and certification methods in an attempt to reject spam while allowing legitimate email to pass through their systems. This interface allows LISTSERV system administrators to determine whether mail originating from their LISTSERV server is likely to be delivered to its final destination based on various standardized mail certification schemas. To assess the deliverability for this LISTSERV site, enter the host name and the IP address from which mail will be sent in the text boxes at the top of the page and click "Submit". Each test response is self-documented and, where appropriate, contains links to external resources describing the protocol in question. Test results are displayed with large green, orange and red icons to help the administrator quickly identify problem areas.

DKIM

The DKIM system is a cryptographic authentication solution that adds signatures to email messages, allowing recipient sites to verify that the message was sent by an authorized sender and was not altered in transit. DKIM uses two keys, a public key and a private key, for this certification. The public key for the domain is stored in the DNS, and the corresponding private key is registered with LISTSERV. Many email clients display a notification for recipients showing whether the mail is certified.

More information about DKIM.

Sender Policy Framework (SPF)

Sender Policy Framework (also known as SPF) is an open DNS-based certification protocol used by recipient sites to verify that the originating IP address is authorized to send email for the domain name declared in the "MAIL FROM" line of the mail envelope. SPF is used to identify messages with forged "MAIL FROM" addresses.

More information about Sender Policy Framework.

Sender ID

Sender ID is a closed DNS-based certification protocol used to verify that the originating IP address is authorized to send email for the domain name declared in the visible "From" or "Sender" lines of the email message. Sender ID is used to prevent spoofing and to identify messages with visible domain names that have been forged.

More information about Sender ID.

Domain Name Tests

This interface also checks the DNS for the presence of A (address), MX (mail-exchanger), and PTR (reverse lookup) records for the host name being assessed. Many email providers require at least an A record, and many also require a PTR record, to certify that mail is actually originating from the host it claims to be coming from.