Spam complaints
In short
Spam complaints are reports made by email recipients who click "report spam" or "junk" on a message you sent. Mailbox providers count these reports against the sender domain and IP, and they influence whether future emails reach the inbox.
For outbound teams, complaints matter more than most metrics. A few reports out of thousands of sends can push messages to the spam folder, so complaint rate is a core health check for any cold email program.
How spam complaints are measured
Complaint rate is the number of spam reports divided by the number of delivered emails. Say a team delivers 2,000 emails in a week and receives 4 complaints. That is a 0.2% complaint rate, which is already high enough to worry about at that volume.
Providers do not always show you every complaint. Some return them through feedback loops, and others only expose aggregated data in postmaster tools. You often see the effect (falling placement) before you see the number.
Why people mark emails as spam
- Irrelevant targeting: The message has nothing to do with the recipient's role or company.
- No clear reason for contact: The email feels generic, with no explanation of why this person was chosen.
- Too many follow-ups: Long sequences with no variation feel like harassment.
- Hard-to-find opt-out: When unsubscribing is difficult, the spam button becomes the easy exit.
- Old or bought lists: Contacts who never heard of you are the most likely to report.
How to reduce spam complaints
Target tightly
Send only to people who match your ideal customer profile and a real role fit. A smaller, relevant list produces fewer complaints than a large, loose one.
Make opting out effortless
Include a clear unsubscribe line or an easy reply such as "not relevant, stop". Honor every request quickly and suppress that contact across all sequences.
Verify and cap volume
Verify addresses before sending, ramp volume slowly on new domains, and stop sequences when someone replies or shows disinterest.
What to do when complaints rise
Pause the affected sequence first. Then check which list, segment, or template produced the reports, since complaints usually cluster. Tighten targeting, rewrite the copy to be more specific, and resume at lower volume.
Do not simply rotate to a new domain. If the cause is poor targeting, the new domain will get the same result.
Spam complaints vs. spam filters
A spam complaint is a human action after delivery. A spam filter is an automated system that decides placement before the recipient sees the message. Complaints feed the filters, so reducing one protects against the other.
Spam complaints FAQs
What is a good spam complaint rate for cold email?
Lower is always better. Most senders aim to keep spam complaints well under 0.1% of delivered emails, and teams treat anything approaching that level as a warning to pause and review targeting, copy, and list quality before sending more.
How do I find out who marked my email as spam?
Usually you cannot see individual identities. Some providers offer feedback loops that report complaints to the sender, and others show only aggregated rates in postmaster tools. Use the data to find the list or template that caused the reports.
Do spam complaints hurt sender reputation?
Yes. Mailbox providers treat complaints as a strong negative signal about the sending domain and IP. A rising complaint rate can move your emails to the spam folder, even for recipients who would have welcomed them.
How can I reduce spam complaints in outbound sales?
Target only relevant contacts, verify email addresses, limit follow-ups, and make unsubscribing easy. Remove anyone who opts out from all sequences immediately, and ramp sending volume gradually on new domains.
