How to add an email account to a user via workflow

If you mean a home directory folder / share, there is a HomeFolderAutoprovisioning policy available in Active Roles which you can trigger by stamping the virtual property edsvaHomeDirectoryNetShare.  Below is the dialog that defines its behavior.  There's one other setting you need to configure that defines the acceptable locations.  This all assumes on-premises home folder storage.  There is a separate set of functionality pertaining to use of OneDrive.

no its a custom directory that we create for each user ( like a home dir but not one) we currently use a PowerShell script to create it I'm working on how to pass the samaccountname variable  from the search I currently do

If you use a Search Activity in your workflow, here's the info on how to grab the users from the result.  The thing to understand is that by using a script with a search activity, the script will run for each object returned.  From the example, you should be able to replace '.distinguishedname' with '.samaccountname' if you feel you need to.  

so it looks like edsaCreateMsExchMailbox = TRUE does not work

I'm getting an error  "Administrative Policy returned an error. Exchange Server-related operation failed. Object reference not set to an instance of an object"

Can you share how you've implemented this?

I used the Update activity and setting the Mail and Alias attribute (Based on the pre2000 login)  save the attribute  then set the create mailbox attribute

Mmmm... though probably not the source of the error, the contents of 'mail' are determined by your Exchange org's addressing policy so you should not be trying to set the mail attribute.

Does your Active Roles service account have Recipient Management permissions in Exchange?

The account does have permission i tried removing the mail attribute still the same error