Here are some steps that worked for me in converting a user mailbox to a shared mailbox.

Info: You can convert the following mailboxes from one type to another

  • User mailbox to resource mailbox
  • Shared mailbox to user mailbox
  • Shared mailbox to resource mailbox
  • Resource mailbox to user mailbox
  • Resource mailbox to shared mailbox

Example reason why you might wan’t to do this:

You have a mailbox account with the name of  bookclub and are looking make it a shared account because its consuming a license. To address this we will convert it to a shared mailbox account by issues the following commands in the Exchange Management Shell

[PS] C:\Windows\system32>Set-Mailbox "bookclub" -Type Shared

 

If you have multiple accounts, the following steps may apply to you

[PS] C:\Windows\system32>Import-CSV "C:\work\import.csv" | foreach {Set-Mailbox -Identity $_.user -Type Shared}

 

Please note the following csv document formatting:

User
"jermsmit Internal"
"jermsmit Sales"
"jermsmit Local"
"jermsmit PR"
"jermsmit Recruiter"

Ref: http://technet.microsoft.com/en-us/library/jj710164%28v=exchg.150%29.aspx