You can request a postal vote on the website, without having to go to a post office in person.
Who can use the application to submit an electronic request for a postal vote?
It cannot be requested by voters who are residents in Spain and are temporarily abroad, or by voters who are residents abroad and request it from their country of residence.
The Electoral Census Office must approve the request, so that it can send the documentation for voting to the address you have indicated in your request.
It can be requested from the date of the announcement until 24th April 2021.
You can then exercise your right to vote from your own home by handing the envelope with your vote to the postal worker on the day they come to take your documents.