scrlttr2 as a letter template? (Together with
mailmerge in case that is relevant.)
How can I use sections or headings inside of a long letter to structure it? Of course, I don't want to make use of a deeply-nested structure as in a scientific document, but just small headlines. They may not be a lot larger than the usual text and may just be bold. That is enough.
I've found this German website, but it only eplains how/that you can use sections outside of the letter. But I want them to be part of the letter.