List hygiene
Keep an IGSendMail list healthy: verify before large sends, re-engage or remove unengaged contacts, and clear out hard bounces on a regular cadence.
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List hygiene is the work of keeping the addresses you send to real and the people behind them interested. It is unglamorous and it is the highest-return thing you can do for delivery. When you finish this page you will have a cadence you can actually keep and a policy for what to do with contacts who stop responding.
Why a stale list costs you#
Mailbox providers decide where your mail lands by watching how recipients treat it. The signals that matter most are the ones a stale list produces in quantity.
Bounces. An address that no longer exists rejects your message. A high bounce rate reads as a sender who does not know who is on their list, which is a pattern spam senders have.
Complaints. Someone who forgot they signed up marks your email as spam. A small number of complaints does real damage, far more than the same number of unsubscribes.
Silence. Contacts who never open anything push your engagement rate down. Providers use engagement as a signal, so mail to people who ignore you makes it harder to reach the people who do not.
Spam traps. Abandoned addresses are sometimes recycled by providers into traps. There is no way to spot one by looking at it, which is exactly why old addresses are dangerous and why removing long-dormant contacts is not a waste of a contact.
Verify before large sends#
Verification checks whether an address can actually receive mail and returns deliverable, undeliverable, or risky. Run it over a list before you send to it at scale, especially when the list is old, was imported from another system, or has not been mailed in months.
Act on the result like this:
- Undeliverable. Remove. These will bounce.
- Risky. Handle deliberately. Excluding them from large sends is the cautious call, and it is the right one when you are warming a domain or your recent bounce rate has been high.
- Deliverable. Send.
Verification is metered per address, so verify what you need rather than the whole account by reflex. Full detail on running it is on Email verification.
Careful
Verification tells you an address exists. It does not tell you the person wants your email. A verified list of people who never asked to hear from you still generates complaints.
Remove hard bounces#
A hard bounce is a permanent rejection: the mailbox does not exist, or the domain does not accept mail. Hard-bounced addresses are suppressed automatically, so they will not be mailed again.
Your job is the follow-up. Check bounces after each campaign. A campaign that bounces at a couple of percent is normal for an older list. A campaign that bounces at ten percent means the source of those addresses is bad, and the fix is upstream: a form with no validation, a purchased file, a badly parsed import. Find it and stop it, because cleaning the symptom every month is more work than fixing the cause once.
Soft bounces are different. A full mailbox or a temporary server problem resolves on its own, so a single soft bounce is no reason to remove anybody. Repeated soft bounces to the same address across several campaigns are, in practice, a dead mailbox.
See Bounces and complaints for how these are processed.
A re-engagement then removal policy#
The hardest habit is deleting contacts. Here is a policy that makes it a routine decision rather than an argument.
Define unengaged in writing
Pick a window and hold to it. A reasonable default is: subscribed more than 90 days ago, and no open or click in the last 180 days. Adjust for your sending frequency. If you mail once a quarter, 180 days is only two campaigns, so stretch the window.
Build the segment
Create a segment with those conditions. Because segments are evaluated at send time, this one stays accurate without maintenance.
Send a short re-engagement campaign
Two or three emails over a couple of weeks. Be direct: they have not opened anything in a while, do they still want to hear from you. Give one clear action, a link to click or a preference to confirm. Keep the design plain, because a heavy template to a cold audience is a complaint waiting to happen.
Wait two weeks, then check who responded
Anyone who opened or clicked has re-qualified and drops out of the unengaged segment on their own.
Remove the rest
Delete or unsubscribe the contacts who did nothing. This is the step people skip, and skipping it makes the previous four pointless. A smaller list that gets read outperforms a larger list that does not.
A cadence you can keep#
Pick times, put them in a calendar, and do them whether or not the numbers look worrying.
| When | What |
|---|---|
| After every campaign | Check the bounce and complaint rates. Investigate a bounce rate above a few percent. |
| Monthly | Review new signups for junk: role addresses, obvious typo domains, duplicate names from the same source. |
| Quarterly | Run the re-engagement and removal cycle on the unengaged segment. |
| Before any send over 10,000 | Verify the audience if it has not been verified in the last 90 days. |
| Annually | Verify the whole active list, and remove anyone who has been on it a year without a single open or click. |
Tip
Track your active contact count, not your total contact count. Total contacts flatter you. Active contacts is the number that predicts revenue and the number that predicts whether your next campaign reaches the inbox.
Prevention beats cleanup#
Most hygiene problems are acquisition problems arriving late.
Use confirmed signup on your forms where you can, so an address is only added after the owner clicks a link. Never buy or rent a list. Never import a file whose origin you cannot explain. Make unsubscribing easy and obvious, because someone who cannot find the unsubscribe link uses the spam button instead, and that costs you far more.
Last updated September 10, 2026