If you delete the message in the Gmail web interface under Sent Mail, it will be moved to the Trash folder and eventually disappear, even if you had previously archived it.

Does Gmail Delete old sent emails?

Does Gmail delete old emails? No, Gmail does not delete old emails. Gmail automatically retains all messages except emails in your Trash or Spam folders. Messages in those folders are automatically deleted after 30 days.

How long do sent emails stay in Gmail?

When you delete a message, it stays in your trash for 30 days. After that time, it will be permanently deleted from your account and can’t be recovered.