07/09/2026
Go open your ESP and find your largest suppression segment. Look at who created it and the date.
If the answer is "not sure" and "a long time ago," you found the problem.
Most suppression segments start as a quick fix for one campaign. Someone names it something like "hold_donotsend," uses it once, and never touches it again. Nobody owns it. Nobody empties it. It only grows.
Every send after that, it pulls people out and never puts them back. No error, no warning, no line on the dashboard. The campaign still "sent." It just reached fewer real people than last time, and fewer again next time.
The usual hiding spots:
1. Old campaign exclusions nobody cleared
2. Manual CSV suppressions from a cleanup two years ago
3. One giant "safety" segment everyone's afraid to open
The fix isn't more contacts. It's this: an event triggers a send, an attribute describes a state. The moment you wire a static audience in as a permanent filter, suppression becomes accidental and permanent.
So give every suppression three things: a reason, an owner, and an expiration date. If it can't tell you why someone is in it and when they get out, it isn't suppression. It's a leak with good intentions.
And check your exit rules. The bug is almost never who you excluded. It's that there's no path back in.
Suppression is not a trash can. If your list can only shrink, your lifecycle isn't running.
We'll tear yours down on Customer. io or whatever you're on. Free, no deck, you keep the findings: https://circlstdio.io/ops-audit
