I made last week some freelance translation work for university and they needed my national insurance number to pay the salary. I received a letter and it says:

Dear Ms Pekka ...
Inland Revenue Regulations - Casual Payments

(.. and so on ..)

However, Pekka is a common Finnish male name. This happened in Northern Ireland.
They should have my details and stuff but still.. I mean, it doesn't bother me because when asked I don't define myself in terms of gender but some other ways.

But when you think about names in general, the good assumption is to think that the person is female is eir name ends with 'a'. Finnish, authoritarian in many respects, do not, however, follow the rules when it comes to naming children.