Keeping your audiences healthy

List hygiene is the ongoing work of keeping your audiences full of valid, engaged, consenting recipients. It's the highest-leverage thing you can do for deliverability: a clean list lowers bounces and complaints, raises engagement, and keeps mailbox providers trusting you. A neglected list does the opposite, slowly, until your mail starts landing in spam.

Remove bounces and unsubscribes

MailBlastr does most of this automatically: hard bounces, complaints, and unsubscribes are added to your account-wide suppression list and skipped on every future send. But suppression hides bad addresses from sending — it doesn't prune your source data.

• Periodically clean the source of your contacts (your CRM, signup database) so you stop importing addresses that will just bounce.
• Don't re-add or re-import addresses that previously bounced or complained — you'll just re-suppress them and waste reputation.
• Treat the suppression list growing fast as a warning sign that your acquisition is letting in bad or non-consenting addresses.

Collect valid addresses in the first place

The cheapest hygiene is not letting bad addresses onto the list at all:

• Block bots with CAPTCHA at signup. Bots sign up freely and fill your list with fake addresses that bounce. A challenge such as Google reCAPTCHA, hCaptcha, or Friendly Captcha keeps signups human.
• Use double opt-in. Send a confirmation link the subscriber must click before they're added — this verifies the address is real *and* that its owner wanted in, and supports CAN-SPAM / CASL compliance.
• Verify deliverability with a third-party service. Valid *syntax* (RFC 5322) doesn't mean a live inbox; an address-verification service flags addresses likely to bounce before you ever mail them.

Re-engage, then sunset, inactive contacts

Contacts who never open, click, or reply drag down your engagement signals — and low engagement is itself a spam signal. Major providers like Gmail and Microsoft expect you to mail people who've recently engaged, so as a rule of thumb limit non-transactional sends to contacts who opened or clicked within the last 6 months (adjust for your industry and cadence). Don't keep mailing dead weight forever.

1. 1
   Identify the inactive

   Find contacts with no clicks or replies over a meaningful window (e.g. the last 3–6 months). Lean on clicks and replies rather than opens, which are noisy.

2. 2
   Run a re-engagement campaign

   Send a short "do you still want to hear from us?" message with a clear way to stay subscribed.

3. 3
   Sunset the rest

   Stop mailing — or unsubscribe — contacts who don't re-engage. A smaller, engaged list outperforms a big, dead one on both placement and results.

Monitor your complaint rate

A rising complaint rate is the clearest early warning that a list or a campaign is unwelcome. Keep complaints under 0.1% where you can; treat 0.3% as a red line. If complaints climb, pause, look at what changed (a new segment? a bought list? a tone shift?), and fix the source.

Hygiene checklist

• Only add contacts with explicit consent.
• Let MailBlastr auto-suppress bounces, complaints, and unsubscribes — and don't fight it by re-importing them.
• Review engagement quarterly; re-engage or sunset the inactive.
• Watch bounces and complaints on every campaign in your logs.
• Keep volume steady and warm up new domains — see the warm-up guide.