1. Who are you writing to?
2. Your research
From their portfolio, a footer credit, or your PublicWWW list. Never name a site you haven't opened.
Concrete and positive. Avoid words like "collapsed".
Gives them a reason to care. Written to follow "That probably means…"
Check the post date and who posted it. Posters are often developers, not owners, and the issue may already be solved.
Pick 2–3 that fit their clients. Ideas: WooCommerce customizations, event scheduling or booking, membership areas, ACF-driven content, complex Loopers, outside APIs, custom forms or calculators. Left blank, the placeholder text is used.
Adds: "It's clear {Company} puts a lot of care into …". Leave blank if unsure, never invent it.