Snoozing moves a conversation out of your inbox until it's due. IMAP has no concept of "hidden until Tuesday", so Mailspring creates a folder on your mail server — Mailspring with a Snoozed folder inside it (a Mailspring/Snoozed label on Gmail) — and moves snoozed threads there. That's why the folder shows up in webmail and on your phone, and why it comes back after you delete it: Mailspring recreates it the next time it syncs.

Getting rid of it

The folder is only recreated while Mailspring is running. Quit Mailspring completely (see running in the background) or remove the account, then delete the folder in webmail. If you've uninstalled Mailspring and it still reappears, another computer is still running it with that account.

Choosing where it's created

Some providers don't allow folders inside folders (163.com, 126.com, QQ, Zoho, and Proton among them). Mailspring's log then shows "Could not create required Mailspring folder: Mailspring/Snoozed", and Snooze won't work for that account. You can tell Mailspring to use a different parent folder:

• When adding an IMAP account, fill in Custom Container Folder on the setup form.
• For accounts you've already added, set Default Container Folder (folder/subfolder) at the top of Preferences > Folders. It applies to accounts that don't have their own value.

Enter the name of an existing top-level folder that your provider allows subfolders in — for example INBOX on 163.com or QQ, or Folders on Proton (Mailspring fills this in for Proton addresses automatically). Snoozed then appears as INBOX/Snoozed. Restart Mailspring after changing it.