Why are my emails going to spam?

The usual advice for mail landing in spam is a list of forty things to try. Most of them are about content, and content is rarely the cause. Work through the causes in the order they actually happen, and stop at the first one that is wrong.

1. Check authentication, then check alignment

Open a message you sent in Gmail, choose “Show original”, and read the SPF, DKIM and DMARC lines at the top. All three should say PASS.

If they do, look one level deeper. DMARC passes only when your From: domain matches the domain that passed SPF or signed with DKIM. A message can pass SPF on your provider’s bounce domain and still fail DMARC, because nothing aligned with the domain the recipient actually sees. It is one of the most common causes, and it is invisible if you only check whether records exist.

2. Read what the receiving server told you

Before a provider starts filtering you to spam, it usually starts deferring you. A deferral is a temporary 4xx response with a reason in plain text, such as “unusual rate of unsolicited mail” or “the IP’s reputation is low”. Providers volunteer this before anything has failed.

If your platform shows you only “delivered” or “failed”, ask for the raw response. Deferrals concentrated at one provider point to reputation with that provider. Deferrals spread across all of them point to something about you, usually authentication or volume.

3. Look at who you are sending to

Complaints and bounces are the reputation you build with each message. Three habits cause most of the damage:

• Mailing addresses that have not engaged in a long time. Old addresses turn into spam traps, and silent recipients teach filters that nobody wants your mail.
• Lists you did not collect yourself. Bought or imported lists carry other people’s complaints with them.
• Ignoring hard bounces. Every repeat send to an address that does not exist tells the provider you are not maintaining your list.

Gmail and Yahoo both want your complaint rate below 0.3%, and Gmail suggests aiming for 0.1%. Our bulk sender requirements post has the full rules.

4. Check whether you changed something

Spam placement that starts suddenly usually has a date. A new sending domain, a new IP, a jump from a few hundred messages a day to tens of thousands, or a new list import. Providers treat sudden change as suspicious, because a compromised account looks exactly like that. Warming up exists for this.

5. Only then, look at content

Content matters at the margins: a link shortener, a mismatch between link text and the real destination, an image with no text, a missing unsubscribe link. Fix these, but expect small gains. If the first four steps are clean, content is rarely what is holding you back.

What not to do

Do not switch to a new domain to escape a bad reputation. It starts with no reputation at all, which filters treat with suspicion, and the habits that damaged the first domain will damage the second.