In Australia, one way you can apply for a postal vote is by sending an application form by mail to the Australian Electoral Commission—the nonpartisan government agency responsible for overseeing federal elections.

Political parties like our centre-right–to–far-right LNP and centre-left–to–centre-right Labor will often send you a letter, in the lead-up to an election. Inside that letter will be an application form, and a reply-paid envelope addressed to the party headquarters. But the address doesn’t say “LNP party headquarters”, it says something like “postal vote centre”.

If you fill out the form, I believe the parties are obligated to send it on to the AEC. But there is no law preventing them from harvesting your data to use for marketing purposes before they do so. Because political parties have exempted themselves from a lot of the usual privacy laws.

There have also been accusations that they might delay sending your details on by a few days if you’re from an area less likely to vote for them. Increasing the chances your postal vote doesn’t arrive in time for you to actually use it. Not sure how founded that is, and I doubt it would be legal, but it also may be difficult to prove.