To send a letter to someone via internal mail, you need to know the internal mailing code for the person or the organisation. This code refers to a physical mail room to which your letter will be sent. It is sometimes abbreviated to HS ("hämtställe" in Swedish).
The internal mailing code is indicated by a number, e.g. HS 31. You can find out which internal mailing code to use for a particular person in the employee directory database, Lucat. You can also see which internal mailing code someone has by using the search field here on the Staff pages.
The Faculty of Social Sciences, the School of Social Work and the Department of Political Science used to have different internal mailing codes from other organisations in the Paradis area, but from May the number 31 will apply to the whole area. Don't forget to write the name of the recipient and the department/unit on the envelope!