Spammers, and even more scammers, have all the more reason to butter you up with compliments actually.
For example, to not be reported for spamming, or, well, because they want to scam you. You’ll get some weird messages if you stay around, you’ll see.
If you can’t find anything at all, it might be due to the message and up/download issues the site had yesterday for a few hours.
I’m not sure what exactly you mean by sending push notifications to “someone”? You can either reply to messsages you get or you can send messages to sellers (only to sellers, as only sellers have the “Contact Me” button, which is to prevent buyers from getting spammed by sellers all the time) but you’re not supposed to send messages other than when someone contacts you to ask about your gig/an order.
If you randomly send messages to other people, they can report you for spamming and that might lead to your messaging abilities being restricted temporarily, or even to your account being suspended. Spam = sending unsolicited messages to anyone without intending to maybe buy their gig, is not permitted.
If you get messages, then you’ll be able to reply to them in a box below the messages.
If you intend to buy from a seller and want to ask them something, you can find their “Contact Me” button on their profile page and message them through that.
Anything else (contacting random people to promote your gig, asking for tips, etc.) is considered spam.