Spam complaint rate calculator

Monitor your complaint rate against ISP thresholds to protect your sender reputation before it's too late.

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Complaint rate / inputcomplaintsfig.

Emails sentSpam complaints

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0.0400%

Spam complaint rate

4 complaints / 10,000 sent

Excellent

ISPs (Gmail/Yahoo) expect complaints under 0.1%.

Tier	Complaint rate	What it means
Excellent← YOU	≤ 0.05%	Well within every ISP threshold.
Good	0.05–0.1%	At the common 0.1% ceiling — watch it.
Warning	0.1–0.5%	Above ISP limits; expect throttling.
Critical	> 0.5%	Blocks and blacklisting likely.

Thresholds

The 0.1% line you can't cross

Complaint rate is the share of recipients who hit 'report spam'. It's the single fastest way to wreck a domain.

Gmail and Yahoo expect complaints under 0.1%. Cross it and you'll see throttling, then blocks.

Low complaints come from real permission, accurate targeting and an easy, honest unsubscribe.

FAQ4 entries

Still curious? Our team responds in under an hour.

Complaint rate = (spam complaints ÷ emails sent) × 100. Even tiny percentages matter — the safe ceiling is 0.1%.

Under 0.05% is excellent. 0.1% is the common ISP ceiling; above it you risk throttling, and above 0.5% you risk blocks and blacklisting.

Send only to people who expect to hear from you, sharpen targeting, set clear expectations, and make unsubscribing one click away.

From your ESP/SMTP provider's reports and from feedback loops (FBLs) offered by mailbox providers like Yahoo and Microsoft.

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