Deny-list for contact/spam form

[CGillen]

Descriptive summary

#2306 Added a honeypot style spam filter. This has brought down our spam list considerably, but some still get through. These messages commonly include inappropriate content. We should develop a way to deny submissions based on a deny-list. We can look for a common deny-list online, build our own, or both.

Expected behavior

Look through Sarah's email
Find inappropriate spam

Actual behavior

No inappropriate spam

Steps to reproduce the behavior

Wait a day or two
Check submission logs

Related work

#2306
#2326

[simholt]

FYI this is still an issue.

[simholt]

@CGillen has work been done on this since 2022? (I think yes?) Spam seems to be minimal; I'm fine to close this if you are.