[mutual connection] suggested I write
to {{first_name}} · Decision-maker you were referred to at {{company}}
Hi {{first_name}},
[Mutual connection] suggested I get in touch. We were talking about [topic you discussed], and your name came up as someone who'd have a view on it.
The short version: [your company] helps teams [what you do]. [Mutual connection] thought it might be relevant to what {{company}} is working on with [their current project].
No pressure either way. Would a quick chat be worthwhile, or should I just send a few lines on how it works?
Alex
P.S. If it's not relevant, just say so. No follow-ups from me.