The short answer is simple: probably more often than you do now.
The better answer depends on how you send, how old the data is, and how quickly new contacts enter your workflow.
Why the schedule matters
Email data decays. People switch jobs, abandon inboxes, mistype addresses, and sign up with temporary accounts they never intend to use long term.
That means a list that looked fine a few months ago may not still deserve your trust today.
A practical schedule by use case
Weekly senders
Quarterly is a reasonable baseline. If you grow quickly or import outside data often, monthly can make more sense.
Daily or high-volume senders
Monthly is safer. When you send often, bad data shows up faster and costs more.
Cold outreach teams
Clean before every campaign. For cold email, list quality is too important to treat as optional maintenance.
Infrequent senders
If you only send occasionally, clean before each major send. Time between campaigns gives bad data more room to accumulate.
After any major import
Always clean before using the data in a real send workflow.
Signs you are not cleaning often enough
- bounce rate is creeping upward
- older segments are underperforming badly
- your ESP has raised a warning
- you are reusing old CSV exports without reviewing them
Make it easy enough to repeat
The best schedule is the one your team can actually keep. If the process is slow, expensive, or annoying, it will keep getting skipped.
MailCull is useful here because the cleanup step can be fast:
- export the list
- upload it to Verify List
- review the results
- export the cleaner version
That makes it easier to treat list cleaning like routine maintenance instead of emergency cleanup.