Microsoft have announced an increase to the maximum auto-expanding archive capacity for eligible Exchange Online mailboxes, from 1.5 TB to 3 TB.

This feature automatically expands an Exchange Online archive mailbox beyond the standard 100 GB, scaling to manage larger volumes of archived email content.

Microsoft plan to begin the rollout in mid-October 2026, with completion expected by the end of the month. Find details in the Message Center announcement here: https://bit.ly/47tEmMZ.