Sending released or or unreleased songs to promo email

Hey everybody, a few weeks ago a DJ duo that I am a huge fan of liked one of my instagram posts, so naturally I reached out and thanked them for the like. They responded with a link to their promo email and said to send a song anytime. After looking around I cant find the email listed on any of their socials/websites etc.. I have a song just about ready to send but Im not sure if I should release it before sending. I know when emailing labels and blogs its standard practice to send unreleased music, but I think this promo email is more for them to find songs for mixes? I am trying to learn the business side ins and outs and if anybody knows what the standard thing to do in the situation is, or has any other tips I would greatly appreciate it! Thanks!