There are two accounts with which you have to work during your stay at the Observatory:
This account is used for al your daily activity when using the STRW/Observatory computing facilities. So your Observatory mail and computer login are associated with this account. It is the account in which you save all your scientific data/software etc.
To your STRW account an email address and box is associated. You can access that mailbox in several ways, see Getting started with your STRW email
For most administrative purposes, such as recording days off, travel declaration and yearly Performance and Development Interview you have to use the ULCN account.
The ULCN account is an account provided to you by the University to allow you to login to all centralized facilities, such as SAP Self Service for all your centralized administrative duties. You will have received an email or paper copy with information about the UCLN account name and password.
Unfortunately the university will also create an email address/box associated to this account and publish this in their Microsoft Exchange Directory for other university personnel to 'find' you. If you want mails to that account forwarded to your STRW mailbox (or any other mailbox), you will have to setup a forward on that ULCN mailbox. Read Setup ULCN mailbox forwarding. If you do not setup forwarding you are bound to overlook important university administrative messages, so please do this asap.