What do I do?

Never thought I'd post something like this, but I really need some advice!

I did a course a while ago, and there was one guy there who insisted on taking a selfie with me just before we left.
Fast forward six months and he's constantly emailing me, saying how much he wishes I was his girlfriend, filling his messages with the heart-eyes and sad-face emojis, complaing about how he never manages to get a girlfriend, how he's going to be alone forever, how he really cares for me, how he wishes I wouldn't hate him, how he wants to earn tons of money to look after his girlfriend, blablabla.
Needless to say, I'm always telling him that I don't want to be with him, it's never going to happen, etc. Several times I've got him to say he'd stop emailing me about this, but then he always does again. Often I just try and ignore his messages, but I don't want to block him as I feel that's a bit... mean. And because now he's just sent me another message saying he was contemplating suicide.

So does anyone have any advice on what I should do?!

I would contact the police and tell them he is a suicide risk, as he needs help. I would also block him, because you don't owe him anything and he needs help from other people.

He's not actually in this country, I don't even know his address, so that doesn't work. And honestly I would just block him now, but what if he did something stupid? Then it would be my fault :/ not for not becoming his gf obviously, but for not trying to talk to him...

You aren't responsible for his actions.