This is an old revision of the document!
https://technet.microsoft.com/sv-se/library/jj710164(v=exchg.150)
Examine the mailbox:
Get-Mailbox -Identity copier@domain.tld | fl *resource*, *recipienttypedetail*
Set the mailbox as a resource account:
Set-Mailbox -Identity copier@domain.tld -Type Equipment