Yes, which is why I also dislike postal voting and want to minimise its use.

What does postal voting have to do with that? they could also force you to film yourself at a polling station...

Well at least where I live (the UK), it's illegal to film in a polling station and the staff in the polling stations should be looking out for that and reporting it.

More importantly (with both postal voting and in-person voting) it's impossible to perform these attacks after the fact, but if you have a receipt of your vote it can be done at any time after you vote.

Unless they also demand that you film yourself continuously up to putting the envelope in a mailbox, they can't be sure you actually mailed the ballot or that you didn't invalidate the result later.

This would risk exposing yourself, and in turn, the intimidator.

But if only one ballot is mailed per citizen, they can be reasonably sure you didn't vote for the competition.