Friday, June 24, 2011

When a user has 15,000+ unread items in the inbox....

We *thought* huge mailboxes (as measured by disk space) could wreak havoc during a migration. Perhaps we are wrong. This is a story about huge inboxes and unread email (the harbinger of problems that plague email systems.)

Last week we moved a client into Exchange 2010 (on-premesis). BUT the Sumatra Exchange insertion tool hung while inserting one user. For hours. Restarting the tool and rebooting boxes didn't help. After much digging we found the problem: that end user had 15,000+ unread emails in her inbox. What was the issue? (no, not why would we migrate a user with 15,000 unread emails in their inbox who probably left the company three years ago....)

The client hit an Exchange threshold. The issue is described in a Microsoft Technet article: Understanding the Performance Impact of High Item Counts and Restricted Views.

The article says: ...In Exchange 2007 ... an acceptable user experience can still be maintained with item counts as high as 20,000 items. We're still researching if that limit changed for Exchange 2010. Our client hit that wall in Exchange 2010.

So who are these big-bad-inbox-boys and girls? Here's a powershell command: (note, I've set a conservative threshold of 10,000 items for just user mailboxes.)

Get-Mailbox -filter {RecipientType -eq "UserMailbox"} -ResultSize unlimited Get-MailboxFolderStatistics where {($ -eq "Inbox" -or $_.Name -eq "Calendar") -AND $_.itemsinfolder -ge 10000} sort-object ItemsinFolder -Descending ft Identity,ItemsinFolder,FolderSize


1 comment:

zyg said...

For Exchange 2013 / Outlook 2013 see:

"Exchange 2013 / Outlook 2013 Large Mailbox / Item Counts"

Not a lot of information there but it's a start (and this is relevant for a few people we have wanting to migrate data from 1990 onward.