[harnhua]

I haven't had much luck reaching out to developers via cold email either. Face-to-face seems to work best. Even phonecalls result in most people activating their anti-sales shields.

As other posters mentioned, a brief, straight-to-the-point subject followed by at most two paragraphs. Personally, I'm not a fan of flowery language either because it sounds a little insincere. There may be cultural differences here.

To Japanese developers, my emails tend to be wordier and often the only form of response seem to be a visit to our site. That's good enough for me, for now.

Not that it's terribly successful, but I usually try to make a (genuine) reference to something the other party has published / written / made before saying something relevant to it like, "for your product X/task X, would you consider trying out something like Y(our product) to see if <benefits> can be realised?"