What bounce rate and complaint rate actually trigger a suspension

Envello auto-pauses an account's sending when its bounce rate exceeds 5% or its complaint rate exceeds 0.3%, whichever hits first. These aren't arbitrary numbers, they're close to the thresholds mailbox providers and AWS SES itself use to judge whether a sender is trustworthy, so an account that crosses them is already at risk of a sending-reputation problem that a pause is meant to catch before it gets worse.

What these rates actually protect

On shared sending infrastructure, one account's bad sending pattern can affect every other account sharing that reputation. A pause at these thresholds exists to catch a problem (a stale list with a lot of dead addresses, a sudden spike in unwanted mail) before it degrades deliverability for the pool it's sending through, not to punish an account for a single bad message.

Why bounce rate matters more than it seems

A high bounce rate signals a list-hygiene problem: sending to addresses that don't exist, or haven't been valid in a long time. Mailbox providers read a high bounce rate as evidence a sender doesn't validate its recipient list, which is a real spam signal even for a sender with genuinely good intentions. Address validation before adding to a send list (checking syntax, disposable domains, MX records) is the actual fix, not just watching the rate after the fact.

Why the complaint threshold is so much lower

0.3% is a much tighter tolerance than 5% bounce, deliberately: a spam complaint is an explicit, active signal from a real person that they didn't want the message, which mailbox providers weight far more heavily than a bounce (which could be a simple typo or an outdated address, not necessarily unwanted mail). A small number of complaints represents real, decisive negative signal in a way a small number of bounces doesn't.

What to actually do before you hit either threshold

Validate addresses before sending rather than discovering they're invalid via a bounce, and treat a rising trend in either rate as the signal to act on, not the moment it crosses the line. By the time an account hits the auto-pause threshold, the underlying problem (a stale list, a mismatched audience) has usually been building for a while.