When your account is created, your available mailbox numbers are set to start with 1 by default.

But if you follow a different sequence or need to set your account to start with a different number, you can set that up in your settings: 

  • Go to Business Settings
  • Click on the tab titled "General"
  • Type the number you'd like your offered mailboxes to start with
  • Click the "Save changes" button to confirm