Do people appreciate unsolicited mails from freelance developers? Seems like spamming to me. Also, if you are looking for work why would you waste time with someone who probably does not have any to offer?
I've been freelance for the best part of the decade, yet whenever I receive a cold-call email from a freelancer looking for work (like the one suggested above), I generally either politely decline or mark as spam (if the tone of the email sounds like I'm one of 200 who were sent the same message body), even if I really could do with someone to help spread my workload.
One key thing, for me, is that giving someone work requires _my_ trust in _their_ abilities. Some people might choose to base trust on a track record of projects listed on a CV, others on viewing someone's source code in a public repo, others might value personal recommendations, others might only trust people who they actually know from a not-too-distant circle of their professional network. I'm mostly in that last two camps. A cold-call email from a stranger: you'd be lucky to get a 2% genuine real-paid-work conversion rate, in my mind. A warm-call (I know that sucks as a term) email from someone I know via work or a conference or some kind of tech situation: far more likely to lead to work.
