The Top Reasons Emails Land in Spam — and How to Fix Each

Spam filters weigh many signals, but the reasons good mail gets filtered fall into a handful of categories. Work through them in order and you'll usually find — and fix — the problem fast.

1. Broken or missing authentication

If your SPF, DKIM or DMARC is missing or misaligned, receivers can't verify you, and your mail looks suspicious. This is the most common cause and the easiest to fix. Run our free authentication checkers first.

2. A blacklisted domain or IP

If your domain or sending IP is on a DNSBL (like Spamhaus), receivers may reject or junk your mail outright. Check your status with our blacklist checker and start the delisting process if you're listed.

3. Poor sender reputation

A new or cold sender has no track record, and a sender with rising complaints has a bad one. Both hurt placement. Warmup is the cure — it builds a positive history gradually.

4. Dirty lists and high bounces

Sending to invalid, disposable or role-based addresses spikes your bounce and complaint rates, which filters punish. Verify addresses with our email checker before you send.

5. Spammy content

Trigger words, ALL CAPS, excessive punctuation and link overload all raise risk. Run your copy through our spam checker — though remember content is only one factor among many.

Put it together

• Fix authentication (SPF/DKIM/DMARC).
• Confirm you're not blacklisted.
• Clean your list.
• Sanity-check your content.
• Build reputation with warmup.

Address these five and you've handled the overwhelming majority of spam-folder causes.