Amazon SES is one of the cheapest, most scalable ways to send email at volume, but that low price comes with strict enforcement. If your bounce rate climbs too high, AWS does not send a warning email and wait. It places your account under review and can pause your sending entirely, cutting off transactional and marketing email at the same time.
The single biggest driver of a high SES bounce rate is a dirty recipient list. This guide explains the exact thresholds Amazon enforces, why SES is so unforgiving, and how to clean your list before every send so you never trip the account-pause wire.
The SES Bounce and Complaint Thresholds
Amazon SES tracks two reputation metrics on a rolling basis, and both have hard limits:
- Bounce rate: SES issues a warning when your bounce rate reaches 5% and can pause your account when it hits 10%.
- Complaint rate: SES warns at 0.1% and can pause sending at 0.5%.
These rates are calculated across a representative volume of recent sends, so a single bad campaign to an old list can move the needle fast. Unlike a dedicated ESP that might throttle you gradually, SES treats a high bounce rate as a sign that you may be a spammer, and account suspension protects the shared reputation of the entire SES platform.
The critical detail most senders miss: hard bounces count against you immediately. There is no grace period for “we did not know the address was dead.”
Why New SES Accounts Are Especially Vulnerable
If your account is still in the SES sandbox or recently graduated to production, you have a low sending quota and almost no reputation history. In that state, even a small number of bounces produces a large percentage. Sending 200 emails with 15 dead addresses puts you at a 7.5% bounce rate instantly, which is enough to trigger a review before you have sent your first real campaign.
This is why list validation matters most at the start. You cannot afford to burn reputation you have not built yet.
What Actually Causes SES Bounces
Not every bad address looks broken. The categories that quietly inflate your bounce rate include:
Hard bounces are permanent failures: the mailbox does not exist, the domain has no mail server, or the account was deleted. Each one counts directly against your SES bounce rate.
Catch-all addresses are the dangerous ones. Many business domains accept every message sent to them, so a fake address like [email protected] looks valid to standard verification tools. These pass basic checks but frequently bounce or get silently dropped at delivery. This is exactly the gap Scrubby is built to close: it runs deeper probes to detect catch-all and risky mailboxes that tools like ZeroBounce and NeverBounce pass through as “valid.”
Role-based and stale addresses like info@ or contacts you have not mailed in a year accumulate bounces and complaints over time as people change jobs and abandon inboxes.
Step 1: Export the List You Plan to Send To
Whether your recipients live in a database, a CSV, or a CRM, pull the addresses you intend to send to through SES into a single CSV with, at minimum, an email column. Do not validate your entire database if you only mail a subset; focus on the addresses that will actually hit SES.
If you are sending to an older segment (anyone you have not contacted in 90 days or more), prioritize that list. Stale segments hold the highest concentration of dead addresses.
Step 2: Validate Before It Reaches SES
Run the exported list through Scrubby before you load it into SES:
- Log in and click Upload List
- Import your CSV
- Map the email column and start the validation job
- Download the annotated results when complete
Scrubby returns each address as valid, risky, invalid, or unknown. Remove every invalid address before sending, and make a judgment call on risky contacts based on how warm the audience is. A typical run on a 10,000-address list finishes in minutes and commonly flags 5 to 20 percent of addresses, which is precisely the range that would otherwise push you past the SES bounce threshold.
Step 3: Handle SES Bounces Automatically Going Forward
Cleaning before you send prevents most damage, but you should also close the loop on bounces that do occur. Configure SES to publish bounce and complaint notifications through Amazon SNS, then automatically add any bounced address to your internal suppression list. That way a dead address can never bounce twice.
SES also maintains an account-level suppression list that captures hard bounces and complaints across your account. Leave it enabled. Combined with pre-send validation, it forms a two-layer defense: validation stops most bad addresses before they send, and suppression catches the rest before they can hurt you again.
Step 4: Warm Up and Send in Waves
For a large or cold list, do not blast everything at once even after validation. Increase volume gradually so SES sees a steady, healthy sending pattern. If a slice of the list does produce bounces, sending in waves limits the percentage impact and gives you a chance to pause before you approach the 5% warning line.
If you also run outbound sequences through a cold-outreach tool like Kali, validate that list with Scrubby too. Bad addresses hurt your domain reputation across every channel, not just SES, so one clean pass protects your transactional, marketing, and outbound sending together.
What to Expect After Cleaning
Senders who validate before loading lists into SES typically see:
- Bounce rate drop from the 5 to 15 percent danger zone down to under 1 percent
- No account reviews or sending pauses
- Higher inbox placement as domain reputation strengthens
- Lower cost per delivered email, since you stop paying to send to dead inboxes
The improvement compounds. A clean list generates better engagement signals, which raises your standing with Gmail and Outlook, which further protects the SES reputation that keeps your account in good standing.
Summary
Amazon SES gives you cheap, scalable sending in exchange for strict reputation discipline. A bounce rate above 5% earns a warning and above 10% can pause your account, taking transactional and marketing email down together. The fix is not complicated: export the list you plan to send to, validate it with Scrubby to strip out hard bounces and catch-all risks, enable SES suppression to catch anything that slips through, and ramp your volume gradually.
Validate before SES ever sees the list, and the bounce threshold stops being something you worry about.
Kristel K.
Content Strategist