You don’t do this often.
Let’s face it. Putting the date at the top and your signature at the bottom isn’t your jam when it’s time to address a letter. Nor is folding pages into crisp thirds to fit inside an envelope. Formal letters just aren’t your specialty.
As far as new jobs go, the good news is that learning how to address a letter is a lot easier than learning to tie a respectable half-Windsor or mastering the mysterious art of polite breakroom chitchat.