Microsoft makes new archiving policy to kill 'mailbox full'

"The plan, which Microsoft refers to as "reimagining archiving," involves automatically moving the oldest items from a user's primary mailbox to an archive location when the mailbox approaches 90 percent of its quota. Administrators will be interested to learn that the function will also temporarily override the current archiving policy and cannot be turned off if archiving is already enabled."

"Microsoft's solution is threshold-based archiving, which will shunt the oldest items to the archive, except for those marked with the "Never Move to Archive" tag set. An archive mailbox still needs to be provisioned and have sufficient space - there is no auto-expanding here, and the process is intended only as a failsafe. Administrators will be interested to learn that the function will also temporarily override the current archiving policy and cannot be turned off if archiving is already enabled."

Exchange Online will introduce threshold-based auto-archiving that moves the oldest items from a user’s primary mailbox to an archive when the mailbox approaches 90 percent of its quota. The feature temporarily overrides existing archiving policies and cannot be disabled if archiving is already enabled. Time-based retention policies remain available but may lag behind surging email volume caused by large attachments and AI-generated content. Messages marked with the "Never Move to Archive" tag will be exempt. An archive mailbox must be provisioned and have sufficient space because auto-expansion is not provided. Folder structure, searchability, and accessibility of archived items are preserved.

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