How to change a Mailbox Id,Identity, Name ?

[DanHuber]

For whatever reason, one mailbox in an Office 365 tenant has the name/Id/Identity/CN set as "admin". I would like to change that to be like the other mailboxes. How can I do this? 

Get-Mailbox -Identity admin | fl *name*,Id*

SamAccountName :                                 admin56315-149665953
UserPrincipalName :                                firstname.lastname@domain.com
DisplayName :                                         Firstname Lastname
SimpleDisplayName :                              
Name :                                                    admin
DistinguishedName :     CN=admin,OU=domain.onmicrosoft.com,OU=Microsoft Exchange Hosted Organizations,DC=redacted,DC=PROD,DC=OUTLOOK,DC=COM
Identity :                                                  admin
Id :                                                           admin

See further below what all the other mailboxes look like.

Problem is that when I select that mailbox, i.e. in Exchange Admin Center to be added to a group or similar, I see not the DisplayName, but "admin".

 

Thanks

Dan

Other mailboxes show:

SamAccountName :                 chris555411804579053
UserPrincipalName :                firstname2.lastname2@domain.com
DisplayName :                         Firstname2 Lastname2
SimpleDisplayName :
Name :                                    firstname.lastname
DistinguishedName : CN=firstname.lastname,OU=sgaim.onmicrosoft.com,OU=Microsoft Exchange Hosted Organizations,DC=redacted,DC=PROD,DC=OUTLOOK,DC=COM
Identity :                                  firstname2.lastname2
Id :                                           firstname2.lastname2

[#2 · Accepted solution]

Simply use the Set-User cmdlet, Set-Mailbox should also do. Or if you are synchronizing from on-premises AD, make the changes there.

[#3]

Thanks a lot @Vasil Michev 

Set-User -Identity firstname.lastname@domain.com -name firstname.lastname

did it! All the fields are now set correctly:

Name :               firstname.lastname
DistinguishedName :  CN=firstname.lastname,OU=redacted.onmicrosoft.com,OU=Microsoft Exchange Hosted Organizations,DC=redacted,DC=PROD,DC=OUTLOOK,DC=COM
Identity :           firstname.lastname
Id :                 firstname.lastname

Many thanks!

Dan