Email deliverability guides

Clear guides to SPF, DKIM, DMARC, spam score, blacklists and reverse DNS. Each guide explains the standard, names typical mistakes and leads to the free test.

Improve email deliverability

Why mail lands in spam and how to fix it: a checklist covering SPF, DKIM, DMARC, reverse DNS, blacklists, spam score and content. With a free test.

Check and set up SPF

The SPF record explained: structure, ~all versus -all, the limit of 10 DNS lookups and the most common mistakes. With an example and a free SPF test.

Check and set up DKIM

DKIM explained: selector, DNS record, 2048-bit keys and the most common mistakes such as a missing key or modified content. With a free DKIM test.

Check and set up DMARC

DMARC explained: the record, policy none, quarantine and reject, alignment, the subdomain policy sp= and the safe path to p=reject. With a free DMARC test.

Test and lower your spam score

How to read the spam score of SpamAssassin and Rspamd: thresholds, typical rules and how to lower the points. With a free spam test.

Blacklist check for your mail server IP

Check blacklists (DNSBL): Spamhaus, SpamCop, Barracuda and others, causes of listings and steps to delisting. With a free test of the sender IP.

Check reverse DNS (PTR) and HELO

Reverse DNS, PTR record and HELO for mail servers explained: forward-confirmed rDNS, typical mistakes and where to set the PTR. With a free test.

An alternative to Mail-Tester: sender.report

sender.report as an alternative to Mail-Tester: a free deliverability test with 68 checks, end-to-end encrypted reports, a mail simulator and self-hosting.

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