How to Reduce Your Mailjet Bounce Rate and Avoid Account Suspension

Mailjet (part of the Sinch group) is a favorite for teams that want transactional and marketing email under one roof, with a clean template editor and a generous free tier. But that accessibility comes with a compliance team that watches deliverability metrics closely. If your bounce rate climbs, Mailjet does not quietly absorb the damage. It flags your account, can throttle your throughput, and will suspend sending outright if the pattern looks like you are mailing an unmaintained list.

The single biggest driver of a high Mailjet bounce rate is a dirty recipient list. This guide breaks down the thresholds Mailjet expects you to hold, why it reacts so quickly, and the exact workflow to clean your list before every send so you never trip the suspension wire.

Why Mailjet Watches Your Bounces So Closely

Every message you send through Mailjet rides on shared IP reputation by default, and on your own reputation once you move to a dedicated IP. High bounce rates tell mailbox providers like Gmail, Outlook, and Yahoo that you are mailing addresses you have not maintained, which is the classic fingerprint of a spammer.

Mailjet protects itself and every other customer on those shared IPs by acting fast:

• Account review and sending holds. Cross a bounce threshold and Mailjet can pause your sending pending a manual compliance review of your list sources.
• Reputation throttling. Even before a full pause, Mailjet can slow your delivery rate so fewer messages actually leave the queue.
• Dedicated IP damage. On a dedicated IP, a spike in hard bounces tanks the reputation you spent weeks warming up, and rebuilding it is slow and painful.

A bounce is never a neutral event. It compounds against your reputation, and it is almost always preventable at the list level.

The Bounce Rates Mailjet Expects You to Hold

Mailjet does not publish one universal cutoff, but its deliverability guidance and industry norms point to lines you should never cross:

• Bounce rate under 5 percent. This is the widely referenced ceiling. Sustained bounce rates above roughly 5 percent put you firmly in review territory.
• Spam complaint rate under 0.1 percent. One complaint per thousand delivered messages is the Gmail and Yahoo standard, and Mailjet mirrors it.
• Healthy target below 2 percent bounces. Strong senders keep hard bounces well under 2 percent. Treat anything above that as a warning, not an acceptable baseline.

The critical distinction: Mailjet separates hard bounces (permanent failures like a nonexistent mailbox) from soft bounces (temporary issues like a full inbox). Hard bounces are the ones that wreck reputation, and they are exactly the ones a clean list eliminates.

Why Your List Goes Bad in the First Place

Even a list that was clean six months ago decays. The usual culprits:

• Natural churn. People change jobs and abandon addresses. B2B email data degrades by roughly 20 to 30 percent a year.
• Typos at capture. Signup forms collect gmial.com and yahooo.com addresses that hard bounce on the first send.
• Purchased or scraped lists. These are riddled with dead mailboxes and spam traps, and they are the fastest route to a Mailjet suspension.
• Catch-all domains. Many business domains accept every address at the server, so standard verification tools return an ambiguous “unknown” and you send blind.

That last category is the one most teams get wrong, and it is where bounce rates quietly hide.

The Catch-All Blind Spot Most Tools Ignore

Standard email verifiers connect to the recipient mail server and ask whether a mailbox exists. On a catch-all domain the server says “yes” to everything, so ordinary tools mark those addresses as unknown or risky and hand the decision back to you. Depending on your industry, catch-all addresses can make up 20 to 40 percent of a B2B list.

Faced with a pile of unknowns, teams do one of two harmful things: delete them all and throw away real, reachable customers, or send to all of them and eat the bounces that get their Mailjet account suspended.

This is precisely the gap Scrubby was built to close. Instead of giving up on catch-all and risky addresses, Scrubby uses a deeper validation process to determine whether the specific mailbox behind a catch-all domain is genuinely deliverable. You recover the reachable contacts other tools discard and drop only the addresses that would actually bounce, which is the difference between protecting your reputation and shrinking your reach.

A Step-by-Step Workflow to Cut Your Mailjet Bounce Rate

Follow this sequence before every meaningful send.

1. Export the segment you plan to mail

Pull the exact contacts for the upcoming campaign, not your entire database. Validating the specific segment keeps costs down and gives you an accurate risk picture for that send.

2. Validate and resolve catch-all addresses

Run the list through a validator that handles catch-all and risky addresses rather than punting on them. Standard clean addresses pass, dead mailboxes get removed, and the ambiguous catch-all contacts get a real deliverable-or-not verdict. Using Scrubby here is what turns a wall of “unknown” results into confident keep-or-drop decisions.

3. Suppress hard bounces and complainers permanently

Mailjet maintains exclusion and suppression lists automatically, but you should mirror that data into your own source of truth so those addresses never re-enter a send from another tool. Reintroducing a known hard bounce is one of the fastest ways to relight a reputation fire.

4. Segment by engagement before you press send

Prioritize contacts who have opened or clicked recently. If you must email a cold segment, warm up gradually rather than blasting the whole list in one shot, which spikes bounces and complaints together.

5. Rebuild the habit at capture

Add real-time validation to your signup and lead forms so typo and disposable addresses are caught the moment they are entered. Cold outreach teams booking meetings through tools like Kali benefit from the same discipline: a validated address list means invites and follow-ups actually land instead of bouncing before the prospect ever sees them.

Keep It Clean, Not Just Clean Once

A single scrub before a big campaign helps, but bounce rates creep back as lists age. Build validation into your routine:

• Re-validate any segment that has not been mailed in 90 days.
• Clean imported or purchased lists before they ever touch Mailjet.
• Watch your bounce and spam rates in the Mailjet statistics dashboard after every send, and treat any upward trend as a prompt to re-clean.

Mailjet gives you the sending infrastructure, but it holds you responsible for who you send to. Keep your hard bounces low, resolve the catch-all addresses instead of guessing, and you protect both your sender reputation and your ability to keep sending at all. Validating your list with Scrubby before each campaign is the simplest insurance against waking up to a suspended account.