The embarrassing version of a follow-up is quoting a problem they fixed last Thursday. The useful version is noticing they fixed it — or that the site has gone down — before you write.
What “changed” means here
Zenvylo only calls it a change when two fetches disagree. Examples: the page loaded and now it does not, HTTPS appeared or disappeared, a booking link (and the provider, if we recognised it) showed up, the viewport tag was added, the response time moved by a large step rather than a small wobble, the title or footer year changed. Each line cites both observations.
The first time you measure a site, that is not a change. There is nothing earlier to compare.
A weekly pass, not a background robot you cannot see
On Today, “Re-check saved” measures up to five saved sites that have a website and are not marked lost. The measurement server also rate-limits audits, so a huge list is a few clicks, not one silent job. That is deliberate: fetching someone else’s site should stay slow and identifiable. The bot says who it is.
When something differs, it stays on the desk until you mark it seen. Then decide: update the proof link, change the email, or drop the lead.
Neighbour comparisons go stale too
A line like “4 of 6 nearby cafés have booking” is only as fresh as those six fetches. Re-run the neighbour comparison before you put it in a second email. The proof page will show the headlines from the comparison you attached, not a new one it invents later.
More on the first email: how to send a proof page. On picking who is worth a first email at all: getting web design clients.