The basic point is this: It’s bad to continually delete and add new lists to MailChimp willy-nilly. There are many reasons, but these are 4 which spring to mind:
1. You lose all the unsubscribes and cleaned emails each time, as well as all the list stats. The best way is to update lists. If someone unsubscribes from the list but you then delete said list to upload a new one, chances are they will be added back in. However, if you update an existing list with any new names, it will add any new people, without creating any duplicates but not allow you to add any who have already unsubscribed. For this same reason, it is always better to unsubscribe someone from a list than to delete them.
2. Poor list maintenance can result in low engagement and compliance issues, which can affect your ability to send or even shut down your account.
3. If you have your website, landing page or Facebook lead ads configured to automatically update a MailChimp list, if you delete or change the list, this breaks to process.
4. If you’re just starting out, the free account is free up to 2k subscribers, Because of duplicated lists you’ll likely hit that limit and start getting charged sooner than necessary 🙁
There. If you’re guilty of this nefarious practice, slap yourself with a wet fish, and stop it. If you were thinking “it might be easier to delete and re-upload a list rather than figure out what groups are all about or how to segment a list”, refrain.