Office 365 Mailbox size

Occasional Contributor
I'm a bit confused what is counted when I see mailbox size if the office 365 admin center? There's a regular mailbox definitely, but is it including Recoverable Items? What about Exchange Online Archive? I think it's not counts in the mailbox box size. As when I'm counting size using API (Exchange web service) I'm getting much more than just regular mailbox size, but seems that in the admin center it's shows only regular mailbox size. Is there any place where Microsoft explains what is taken into counting mailbox size?

Thanks a lot!
1 Reply

The portal reports only the size of the main mailbox, the size of any archive mailboxes is not included. RecoverableItems also has its own quota, that's not counted against the "main" quota.