If you have received any e-mail messages that have been incorrectly identified as junk mail, you can restore them from your junk mail folder by marking them with the Not Junk tag.
Instructions for OWA users: https://helpdesk.it.helsinki.fi/help/10526
Instructions for Outlook users: https://helpdesk.it.helsinki.fi/en/help/10503
See instructions for virtual desktops here.
As the univerisity's e-mail filtering is carried out automatically, there is a small chance that the filtering algorithm classifies genuine e-mail as spam. You should, therefore, check the contents of the Junk folder every now and then.