You can install this blacklist with either uBlockOrigin or uBlacklist. It's still being updated:
https://github.com/laylavish/uBlockOrigin-HUGE-AI-Blocklist
uBlockOrigin & uBlacklist Huge AI Blocklist
A huge blocklist of manually curated sites (1000+) that contain AI generated content, for the purposes of cleaning image search engines (Google Search, DuckDuckGo, and Bing) with uBlock Origin or uBlacklist.
Also works on mobile (iOS, iPadOS, Android) via uBlacklist, as well as pihole/adguard (via Hosts file)
It appears to spawn a curl process to send the email by constructing a string using user-supplied values. I don't know what checks Guile Scheme does on system calls, but I would guess you are vulnerable to command injection here. That's not ideal for something you want to deploy as a micro-service.
libcurl has bindings for Guile, you should use those instead: https://github.com/spk121/guile-curl