Why your emails go to spam, and how to fix it

1. Your email is not authenticated

The most common and most fixable cause. Without SPF, DKIM and DMARC set up for the domain you send from, receivers have little reason to believe the message is yours. Start with the domain checker.

2. You are a new sender

A new domain or a new sending service has no history, so mailbox providers are cautious. Begin with small volumes to people who expect your mail, such as your own team and recent customers, and increase over a couple of weeks. Jumping from nothing to thousands of messages in a day looks like abuse.

3. Your list is old, bought or full of typos

• Messages to addresses that no longer exist bounce, and a high bounce rate damages your reputation.
• Never buy or rent a list. People who did not ask for your email mark it as spam, and some addresses on such lists are traps set to catch senders.
• Remove addresses that bounce for good, and stop mailing people who have not engaged in a long time.
• Use confirmation (double opt-in) on signup forms, so typos and other people’s addresses never reach your list.

4. People mark your mail as spam

Complaints are the strongest signal there is. Google’s guidance is to keep the spam rate reported in its Postmaster Tools below 0.1% and never reach 0.3%. The way to keep complaints low is to email only people who asked, say clearly what they signed up for, send what you promised, and make unsubscribing easy.

5. Unsubscribing is hard

If people cannot find an unsubscribe link, they use the spam button instead. Put a visible link in every marketing message, and add the one-click unsubscribe header that Gmail and Yahoo now expect for bulk mail. Honour requests immediately.

6. The message itself looks wrong

• A subject that misleads, or is in all capitals with a lot of punctuation.
• A message that is one big image, or has no plain-text version.
• Link shorteners, or links whose visible text points somewhere else.
• A From name that suggests another company, or a Reply-To on an unrelated domain.
• Sending from a free-mail address such as @gmail.com through a service. That fails DMARC; use your own domain.

7. Your domain or address is on a blocklist

Check the major blocklists, such as Spamhaus. Listings usually explain why and how to be removed. Our domain checker looks at the Spamhaus domain list for you.

8. Sudden changes in how you send

A spike in volume, a new kind of mail from an old domain, or a sudden surge of bounces all look suspicious. Change gradually, and send different kinds of mail (receipts and newsletters) from different subdomains so one cannot hurt the other.

How to find out which one is yours

1. Send a test to a few addresses you control at different providers (Gmail, Outlook, Yahoo), and see where it lands.
2. In Gmail, open the message, choose “Show original”, and look at the SPF, DKIM and DMARC results. Any that say FAIL are your answer.
3. Register your domain with Google Postmaster Tools to see your domain’s reputation and spam rate, once you send enough volume for it to show data.
4. Fix one thing at a time, from the top of this list, and test again.