Why your emails go to spam

The real reasons transactional mail lands in the spam folder, in the order worth checking, and which popular explanations are myths.

Start with what is measurable

Spam placement feels mysterious because receivers never tell you why. But the causes have a clear order of importance, and the first two are things you can verify in minutes.

1. Authentication

If SPF and DKIM do not both pass, and if DMARC does not pass with alignment, you are not making a deliverability mistake so much as failing a precondition. Major providers treat unauthenticated bulk mail as ineligible for the inbox rather than merely suspicious.

Send yourself a message and check the headers for spf=pass, dkim=pass, and dmarc=pass. If any of them fail, stop here and fix that first.

2. Complaints

When a recipient hits “report spam”, that is the strongest negative signal available to a receiver, because it comes from the person you were trying to reach. Gmail’s guidance is to stay below 0.10%, and it treats 0.30% as the point where filtering tightens.

Complaints on transactional mail almost always mean one of three things: the recipient did not expect the message, the message is promotional in a transactional envelope, or your address list contains people who never signed up.

3. Reputation

Receivers score your sending domain and your sending IP over time. That history is why a single bad campaign has consequences for weeks and why fixes feel slow: you are waiting for new good behavior to outweigh recorded bad behavior.

Two patterns damage reputation quickly: sudden volume spikes, and a rising share of mail sent to addresses that do not exist.

4. List quality

Sending to addresses that bounce tells receivers you do not know who your recipients are, which is what purchased lists look like. Every hard bounce you could have avoided is a small, permanent cost. See bounces.

5. Content and technical hygiene

Last, and much less important than most people assume. What genuinely matters:

• A From: address on a domain you authenticate, with a Reply-To that works.
• Both a plain text and an HTML part, not HTML alone.
• Links on domains you control, not public URL shorteners.
• Text in the message rather than a single large image.
• An unsubscribe mechanism on anything remotely promotional. See one-click unsubscribe.

In Mailverick

You are not guessing about the first four. The portal records an event for every message, and the failures carry a reason: rejected with spam_detected means a receiving server refused the message as spam. spam_reported means a recipient complained. dropped with tenant_domain_spf_not_verified or tenant_domain_dkim_not_verified means the message never left, because authentication was incomplete. The full vocabulary is in the Email Events documentation.

Recipients who complain or unsubscribe are suppressed automatically, so a single complaint cannot become a repeat complaint. Mailverick also scores each sending IP from 0 to 100 based on delivery outcomes, and scores individual recipient addresses from delivery, open, click, and bounce history.

Myths worth dropping

“Spam words” trigger filters. Modern filtering is reputation-driven. Writing “free” in a receipt is not what is hurting you.

A spam-score checker tells you the truth. Those tools test content against static rules. They cannot see your domain reputation, your complaint rate, or your recipients’ behavior, which are the factors that actually decide placement.

More authentication records help. There is no bonus for stacking mechanisms. SPF, DKIM, and DMARC configured correctly is all of it.

Warming up a domain by sending to yourself. Receivers weight engagement from real recipients. Mail to your own test accounts teaches them nothing.

Common mistakes

Sending marketing from your transactional domain. The fastest way to put password resets in the spam folder. Campaign complaints attach to the domain, not to the campaign.

Ignoring complaint and bounce events. They are the only direct feedback you get. Not acting on them is choosing to keep the cause.

Sending to an old list after a quiet period. Addresses decay. A list untouched for a year contains dead mailboxes and spam traps, and sending to them in bulk costs you reputation.

One giant send after months of nothing. Volume patterns matter. A flat profile with a sudden spike looks like a compromised account.

Assuming it is the platform. If your authentication passes and your complaint rate is fine, placement problems usually come from your list or your content, not from the sending infrastructure.

FAQ

Only one recipient sees my mail in spam. Why?

Filtering is per-recipient. Their own history with your mail, their folder rules, and their provider’s model all feed into it. A single recipient is not a signal; a rising share of recipients is.

How long does it take to recover from bad reputation?

Weeks of consistent, clean sending. There is no reset button, and no provider offers one.

Does buying a dedicated IP fix spam placement?

No, and at low volume it makes things worse, because a dedicated IP with little traffic has no reputation to speak of. See shared vs dedicated IPs.

Do images or attachments hurt?

Not on their own. An image-only email with no text is a weak signal, and executable attachments are refused outright, but a normal receipt with a logo is fine.

Can I ask a provider to unblock me?

Gmail and Microsoft both run postmaster tooling that shows your reputation, and Microsoft has a mitigation request form. Neither is a substitute for fixing the cause first.

Last updated: August 2026