Gmail and the spam folder

Gmail judges mail by authentication, sender reputation and recipient behavior. A delivered event means Gmail accepted the message; it does not say which folder it went to.

#Check authentication

In Gmail open the message, choose Show original and look at the summary at the top. You want SPF: PASS, DKIM: PASS and DMARC: PASS. If one fails, fix the domain records first.

#Requirements for bulk senders

Gmail asks senders of large volumes to:

• Authenticate with SPF and DKIM and publish a DMARC record.
• Offer one-click unsubscribe on marketing mail. Broadcasts include the headers; for other bulk mail see Unsubscribe links.
• Keep spam complaint rates low. Gmail's guidance is to stay under 0.1% and never reach 0.3%. usend warns you well before that.
• Send from a domain whose DNS has working forward and reverse records. On the platform's own IPs, that is handled for you.

#Behavior that helps

• Ask new subscribers to reply or move your message to the primary tab; engagement is the strongest signal.
• Keep sending steady. A sudden jump in volume from a quiet domain looks like abuse: Warm up a domain.
• Keep from, subject style and sending domain consistent.
• Remove people who never open. See Audience hygiene.

#If a person finds you in spam

Ask them to open the message, choose Report not spam, and add your address to their contacts. A handful of such actions helps with that user only; reputation is built over weeks.

#Gmail Postmaster Tools

You can register your domain with Google Postmaster Tools to see Gmail's own view of your domain reputation, spam rate and authentication results. It needs a DNS TXT record Google gives you, which you can add next to the usend records. It only shows data once you send enough volume to Gmail users.

More: Why emails go to spam.