ESP bounce and complaint limit checker: how close is your send to a suspension?
In short: Your hard bounce, complaint and unsubscribe rates against the lines Brevo, HubSpot, Amazon SES, Postmark, Instantly, lemlist, SendGrid, Klaviyo and Gmail publish themselves, with how many more bounces the same send could take. Platforms that publish no number are marked as such. Limit: It uses each vendor's published line; a platform can act below it, and several publish no number at all.
Pick your platform and enter emails sent, hard bounces and complaints. The tool shows your rates against that platform's published lines (Brevo can suspend above 2% hard bounces, HubSpot at 5% in a month, Amazon SES reviews at 5% and may pause at 10%) and against every other platform's, each linked to the vendor's own page.
Price: this tool is free. Checking a whole email list is from $9/mo, and the first 100 checks are free with Google, no card. See pricing
The send, or the period your platform measures.
Permanent failures only (5.1.x unknown user, bad domain).
Brevo and HubSpot publish an unsubscribe line too.
- Hard bounce rate
- 3.10%
- Complaint rate
- 0.144%
- Unsubscribe rate
- Not entered
- Platforms you'd be over
- 4
310 hard bounces ÷ 10,000 sent = 3.10%; 14 complaints ÷ 9,690 delivered = 0.144%.
HubSpot
- Hard bouncesUnder, next line 5% or more (189 more on this volume before the first enforcement line)
- ComplaintsOver its enforcement line, 0.1% or more: marketing email may be suspended
How HubSpot counts: Hard bounce, spam report and unsubscribe rates in a specific month. Source: HubSpot KB: resolve email sending suspensions.
Brevo
- Hard bounces
- Over its enforcement line, above 2%: campaigns or account can be suspended
- Complaints
- Under, next line above 0.2%
HubSpot
- Hard bounces
- Under, next line 5% or more
- Complaints
- Over its enforcement line, 0.1% or more: marketing email may be suspended
Amazon SES
- Hard bounces
- Over its advice line, above 2%: recommended maximum
- Complaints
- Over its enforcement line, 0.1% or more: account placed under review
Postmark
- Hard bounces
- Under, next line 10% or more
- Complaints
- Over its enforcement line, 0.1% or more: must stay below
Instantly
- Hard bounces
- Under, next line 5% or more
- Complaints
- Not published
lemlist
- Hard bounces
- Under, next line 10% or more
- Complaints
- Not published
SendGrid (Twilio)
- Hard bounces
- Under, next line above 5%
- Complaints
- Over its advice line, above 0.1%: twilio calls this excessive
Klaviyo
- Hard bounces
- Over its advice line, above 2%: needs attention
- Complaints
- Over its advice line, above 0.05%: needs attention
Mailchimp
- Hard bounces
- Not published
- Complaints
- Not published
Mailgun
- Hard bounces
- Not published
- Complaints
- Not published
Gmail and Yahoo (spam rate)
- Hard bounces
- Not published
- Complaints
- Over its advice line, above 0.1%: google's target: keep below
| Platform | Hard bounces | Complaints |
|---|---|---|
| Brevo | Over its enforcement line, above 2%: campaigns or account can be suspended | Under, next line above 0.2% |
| HubSpot | Under, next line 5% or more | Over its enforcement line, 0.1% or more: marketing email may be suspended |
| Amazon SES | Over its advice line, above 2%: recommended maximum | Over its enforcement line, 0.1% or more: account placed under review |
| Postmark | Under, next line 10% or more | Over its enforcement line, 0.1% or more: must stay below |
| Instantly | Under, next line 5% or more | Not published |
| lemlist | Under, next line 10% or more | Not published |
| SendGrid (Twilio) | Under, next line above 5% | Over its advice line, above 0.1%: twilio calls this excessive |
| Klaviyo | Over its advice line, above 2%: needs attention | Over its advice line, above 0.05%: needs attention |
| Mailchimp | Not published | Not published |
| Mailgun | Not published | Not published |
| Gmail and Yahoo (spam rate) | Not published | Over its advice line, above 0.1%: google's target: keep below |
Lines are each vendor’s own help page, read 2026-10-01; “not published” means the platform says a limit exists but gives no number. Advice lines (“needs attention”, “keep below”) are not enforcement. Your platform’s own dashboard figure wins: SES, for one, counts only some bounces over a volume you can’t reproduce.
Next step
Over 2% hard bounces is over the strictest published line. Clean the list before the next send.
Every line above measures damage after it's done. Most hard bounces are addresses that no longer exist, and a mailbox check finds them before they are mailed, so the next send starts under every platform's line.
No list right now? This tool stays free, no account, so bookmark it for next time. Ctrl+D (⌘+D on a Mac)
Ready to verify now? Verify the list
Sample result
3.10% hard bounces is under HubSpot's 5% line, but 0.144% complaints is over its 0.1%.
- Hard bounce rate
- 3.10%
- HubSpot bounces
- Under 5%, 189 to spare
- HubSpot complaints
- Over 0.1%
What this means for you
The same send is over an enforcement line at 4 platforms; Brevo would already suspend at 2%.
- Brevo, HubSpot, SES, Postmark lines
- Instantly and lemlist auto-pause
- Headroom before the first line
- "Not published" where it isn't
- Bounce limits
- Complaints
- Suspension
By SimpleVerifier Team · Last updated · Runs in your browser; nothing you paste is sent to us
How do I get the bounce rate under the line before the next send?
- Remove the addresses that already hard-bounced; your platform usually suppresses them already.
- Upload the rest of the list at /verify. Every address gets a live mailbox check, and valid, risky and invalid download as separate files. The first 100 email checks are free with a Google sign-in, no card.
- Send the next campaign to the valid file only.
How do I check my bounce rate against my ESP's limit?
- Pick the platform you send from.
- Enter emails sent, hard bounces and spam complaints for the send or the period your platform measures (HubSpot: a month; Brevo: the last 24 hours).
- Read your rates against that platform's lines, and how many more bounces the same volume could take before the first enforcement line.
- Check the table: the same numbers against every other platform, in case you're moving or sending from two.
Example
- You enter
- HubSpot picked; 10,000 emails sent, 310 hard bounces and 14 spam complaints.
- You get
- A 3.10% hard bounce rate and a 0.144% complaint rate (14 of 9,690 delivered). HubSpot: bounces under its 5% line with 189 more to spare, complaints over its 0.1% line. Across the table the same send is over an enforcement line at Brevo, HubSpot, Amazon SES and Postmark.
- Limits
- Runs in your browser; the lines are each vendor's page as read on the date shown.
Which platforms publish a bounce limit?
Fewer than you'd think. Of the vendor help pages read for this tool, Brevo publishes the lowest enforcement line (hard bounces above 2% can suspend campaigns or the account), HubSpot suspends at a 5% hard bounce rate in a month, Amazon SES places an account under review at 5% and may pause sending at 10%, and Postmark requires under 10%. Instantly auto-pauses a campaign at 5% by default and lemlist at 50%.
Mailchimp and Mailgun say thresholds exist without publishing a number, and SendGrid and Klaviyo publish advice rather than enforcement lines. The tool marks those as not published or as advice and doesn't fill the gap; numbers quoted on third-party blogs often don't appear on the vendors' own pages. The full comparison is in bounce rate thresholds by platform.
Why doesn't my platform's dashboard show the same rate?
Because each platform counts differently. This tool divides hard bounces by emails sent and complaints by emails delivered. Amazon SES counts only hard bounces to domains you haven't verified, over a "representative volume" rather than a fixed window, and says you can't reproduce its figure from your own counts. Smartlead divides by the campaign's total leads, Instantly waits for 200 sends and lemlist for 100 contacted leads.
Use this to see how much headroom a send has, and trust the platform's own reputation page for the number it acts on.
Complaint lines are much tighter
Every published complaint line is an order of magnitude below the bounce lines: 0.1% at HubSpot, Postmark and Amazon SES review (0.5% may pause), 0.2% at Brevo. Gmail asks bulk senders to keep the Postmaster Tools spam rate below 0.1% and never reach 0.3%. One complaint per 1,000 delivered is already at most of these lines; the spam complaint rate calculator shows what a planned send can absorb.
Published lines, platform by platform
| Platform | Hard bounces | Complaints |
|---|---|---|
| Brevo | Above 2%: suspension | Above 0.2% |
| HubSpot | 5% in a month: suspension | 0.1% |
| Amazon SES | 5% review, 10% may pause | 0.1% review, 0.5% may pause |
| Postmark | Must stay below 10% | Below 0.1% |
| Instantly | 5% auto-pause (adjustable) | Not published |
| lemlist | 10% alert, 50% auto-pause | Not published |
| Mailchimp, Mailgun | Not published | Not published |
Each vendor's own help page, read 1 October 2026 (Amazon SES and HubSpot re-read 2 November 2026).
Who uses this tool, and for what?
- Marketing ops
- Check a campaign's numbers against the platform's line before deciding whether to send the next one.
- Cold emailers
- See where a sequence's bounce rate sits against Instantly's or lemlist's auto-pause.
- Developers on SES
- Estimate headroom under the 5% review line while the reputation dashboard catches up.
- Agencies
- Show a client which platforms their list would already be suspended on.
What can’t this tool tell you?
- It uses each vendor's published line; a platform can act below it, and several publish no number at all.
- Your platform's own rate can differ from this one, because each counts bounces and the window differently.
- Lines change; each is dated to when the vendor page was read.
- It can't tell which addresses on your list will bounce next. That needs a mailbox check.
Common questions
- What bounce rate gets an Amazon SES account suspended?
- SES says it places an account under review at a bounce rate of 5% or more and may pause sending at 10% or more, and recommends staying below 2%. Only hard bounces to domains you haven't verified count.
- What is HubSpot's bounce rate limit?
- HubSpot's knowledge base says marketing email may be suspended at a 5% hard bounce rate, a 0.1% spam report rate or a 3% unsubscribe rate in a specific month.
- Is a 3% bounce rate bad?
- It is under most published enforcement lines but over Brevo's 2% and Amazon SES's recommended 2%. Treat anything over 2% as a list problem to fix before the next send.
- Does it send my numbers anywhere?
- No. The calculation runs in your browser.
Sources
Clean the list before the next send.
A bounce report only tells you about the addresses you already mailed. The rest of the list has the same kinds of dead mailboxes in it, and each one becomes a hard bounce recorded against your domain the moment you send.
- A real SMTP mailbox check on every row, before anything is sent
- Dead and mistyped addresses split out, so they never reach your sending tool
- Catch-all, disposable and role addresses flagged alongside
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