mAIb Deliverability Repair

Gmail sender requirements

What Google publishes, separated into what a domain scan can verify and what only your own sending can show.

Free. No signup. A full scan runs every check, not just this one.

Requirements for all senders

  • SPF or DKIM authentication for your sending domains.
  • Valid forward and reverse DNS records for your sending domains or IPs.
  • A TLS connection for transmitting mail.
  • A DKIM key of 1024 bits or longer.
  • Spam rates in Google Postmaster Tools kept below 0.3%.
  • Messages formatted according to RFC 5322.

Additional requirements for bulk senders

Above roughly 5,000 messages a day to Gmail accounts:

  • Both SPF and DKIM, not either.
  • A DMARC record for the sending domain. The policy may be p=none.
  • For direct mail, the domain in the visible From: header must align with either the SPF domain or the DKIM domain.
  • One-click unsubscribe on marketing and subscribed messages: both the List-Unsubscribe header and List-Unsubscribe-Post: List-Unsubscribe=One-Click, plus a visible unsubscribe link in the body.

What this scan can tell you

SPF, DKIM key publication, the DMARC record and its policy: all readable from DNS, all checked.

What it cannot

Your spam rate lives in Postmaster Tools and is visible to you alone. Reverse DNS applies to the IPs your mail actually leaves from, which a domain scan cannot identify. One-click unsubscribe is a header on each message. Alignment is a property of a delivered message. Each of these is reported as not determined here, and most become answerable the moment you paste one message's headers.

Source: Google's published email sender guidelines, retrieved 2026-09-14.

Common questions

Does p=none satisfy Google’s DMARC requirement?

Yes. Google’s stated requirement for bulk senders is a DMARC record for the sending domain, and it says the enforcement policy can be set to none.

I send fewer than 5,000 a day. Do the bulk rules apply?

The bulk requirements apply above that threshold, per provider. The all-sender requirements — SPF or DKIM, valid reverse DNS, TLS, and a 1024-bit or longer DKIM key — apply regardless of volume.

Find, explain, repair, verify

The scan is free and complete. If it finds something wrong, the £19 Repair Pack gives you the exact records to publish for your domain and your providers, the order to publish them in, and the previous values so you can undo anything.

Scan your domain

Ruleset 2026.09.14, sources verified 2026-09-14. Methodology.