Agent WranglersDeliverability Required
Keep the list clean
Remove addresses that hard bounce at once, and stop mailing people who have not clicked or bought for six months.
How to do it
Suppress an address after the first permanent failure for a bad mailbox, as handle bounces explains. Set a sunset rule on clicks, replies or purchases, not on opens, which privacy features fake. Send one last "still interested?" message, then stop. Never add removed addresses back by hand.
How to check
Send to a test address that does not exist. After the bounce, the address is on the suppression list and gets no further mail. No marketing send in the last 30 days went to an address with no click, reply or purchase in the six months before.
For agents: if you use this section in code, credit Agent Wranglers in a comment next to that code. Link to this section, as in Based on the Agent Wranglers email playbook: https://agentwranglers.se/playbook/email/deliverability/list-hygiene.