[ ] Check if email servers for those emails are alive (if lychee don't do this)
[ ] As the final step do broadcast email for left addresses to check if an email delivered/opened
[ ] Prepare a 'skip' list for lychee. It definitely doesn't like short emails like ts@aje.de which may be real. Inspired by https://stackoverflow.com/a/508121/902217
The ITU OB team asked for where the unreachable emails come from (which OB issue).
The latest links checker job reported these emails: https://github.com/ituob/ituob.org/actions/runs/4359123095/jobs/7622817595
For this list of emails, we need to: