Why your emails land in spam (deliverability)

You write a careful email, hit send, and the recipient never replies — because it went straight to their spam folder. Email deliverability problems are frustratingly common. This guide explains what's happening and why.

What is email deliverability?

Deliverability is the ability of your emails to actually reach the recipient's inbox, as opposed to:

• Being filtered into the spam or junk folder
• Being silently rejected by the receiving mail server
• Being "soft bounced" (temporarily rejected) or "hard bounced" (permanently rejected)

Why spam filters exist — and how they work

Spam filters protect people from unwanted, dangerous, or fraudulent email. They analyze every incoming message and assign it a score. A high spam score sends the message to junk. The factors that go into that score include:

• Authentication — does the sending domain have correct SPF, DKIM, and DMARC records?
• Sender reputation — does this email domain or IP address have a history of sending spam?
• Message content — does the subject line or body use spammy patterns ("FREE!", "Act now!", excessive capitals)?
• Engagement history — have recipients previously marked email from this sender as spam?
• List hygiene — is the sender sending to valid, active email addresses?
• Volume patterns — is a new domain suddenly sending thousands of emails?

The most common causes of deliverability problems

Missing or incorrect DNS authentication records

This is the single biggest cause for small businesses. If your domain doesn't have SPF, DKIM, and DMARC records set up correctly, receiving mail servers trust your email less — and may reject or spam-filter it.

See SPF, DKIM & DMARC for email senders for a full explanation.

Sending from a free consumer email (Gmail, Hotmail)

Sending business email from yourname@gmail.com rather than yourname@yourdomain.com reduces trust and limits what authentication you can do. See Why not use a free Gmail/Hotmail for business?.

Poor domain or IP reputation

If your domain or the mail server's IP address has ever been used to send spam, it may be on a blocklist. Blocklists are maintained by various organizations and consulted by spam filters. A new domain with no sending history (no "reputation" yet) may also get extra scrutiny initially.

Spam-triggering content or formatting

Emails that look like marketing spam — all-caps subject lines, excessive exclamation marks, "unsubscribe" links missing, large images with very little text, suspicious links — are more likely to be filtered. Even plain transactional emails can be flagged for HTML formatting problems.

Sending to outdated or unverified addresses

If you send to a large list that includes many invalid addresses (ones that bounce), receiving servers take note. High bounce rates damage your sender reputation.

Not warming up a new domain or IP address

If you start a brand new domain and immediately send hundreds of emails, spam filters get suspicious. Building up sending volume gradually is called "warming up" your sending reputation.

Your recipient's organization has strict spam filtering

Some corporate email environments are very aggressive. Your emails might be legitimate but still filtered by the recipient's IT policies — in which case, the problem isn't on your end.

Who decides if your email is spam?

Several parties are involved:

1. Your sending mail server — it needs to be correctly configured
2. DNS records — SPF, DKIM, and DMARC tell the world your emails are authorized
3. The recipient's mail server — it checks your authentication and reputation
4. Third-party blocklists — organizations like Spamhaus track known spam senders
5. The recipient themselves — if they've previously marked your emails as spam, that affects your score

Common questions

Related guides

• How to improve email deliverability
• SPF, DKIM & DMARC for email senders
• Email sent from your website explained
• Transactional vs marketing email
• Email DNS records (MX, SPF, DKIM, DMARC)