2021-12-15 UTC
# 
aaronpk e.g. for my twitter profile twitter.com/aaronpk it links to a t.co URL, but you could send a webmention from twitter.com/aaronpk to my webmention endpoint with a target URL of the t.co URL. the webmention is valid and my webmention endpoint can validate it, but it has to be willing to accept a webmention for the t.co domain