I may be wrong to interpret \url a synonym of \from based on the documentation, as \from has only one parameter though. Test:You can use
\url[aurl]as well, which behaves like \from[#1].
\useURL[author_email][mailto:invalid@invalid.invalid][][A Name]
\setupinteraction[state=start]
\starttext
\from[author_email]
\url[author_email]
\stoptext