We recommend to always warm-up your inbox.
Inbox providers like Gmail or Outlook can flag your email address as suspicious if its activity is not consistent over time. If it varies too much, your emails can land in spam once again.
When it's warmed-up, an email address needs to be kept warm. Thanks to a "cruising pace" of sending volume, there won't be any huge gap in the activity of your inbox and providers won't flag it as spammy or suspicious.
This is why, even after your warm-up process is over, Warmbox will automatically continue to send emails from your inbox.
You can deactivate the warm-up to stop the "Always warm-up" process.