After moving/migrating all mailboxes from Exchange 2003 to Exchange 2010, you have to update several objects to Exchange 2010 level. One of these types of objects are mail contacts. If you see the error message :
“the object must be upgrade to the current Exchange version. After the upgrade the object cannot be managed by an earlier version….”
You can solve this by typing in one of the next commands in powershell, (actually you fill in the customattribute1 field with ‘nothing’)
Get-MailContact -resultsize Unlimited | Set-MailContact -CustomAttribute1 $null
Get-MailContact -resultsize Unlimited | Set-MailContact -CustomAttribute1 Update
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