Changing primary smtp address via policy

Hello everyone,

i am having troubles to change the default policy for smtp email address format.

We would like to have the following format: 1 letter of the first name.surname@domain.tld

(i.e. J.Dohn@domain.tld)

This should not be hard i thought... and found quickly enough the parameters needed:

%1g.%s@domain.tld

Unforunately Exchange Server 2013 does not like it and tells me i have an error in the parameters. 

So i went to powershell:

The policy is created without error, i then try to apply it and it stops with an error. 

New-EmailAddressPolicy -Name "Policy" -IncludeRecipients MailboxUsers -EnabledEmailAddressTemplates "SMTP:%1g%s@domain.tld"

This policy without the "." works and can be applied. Any idea on how i can get my "." between the first letter of the first name and suranme?

Thanks for any help!

Regards

Christian