cross-post
or cross·post
[ kraws-pohst kros‐ ]
/ ˈkrɔsˌpoʊst ˈkrɒs‐ /
verb (used with or without object)
to post (the same message) to two or more message boards or electronic mailing lists at the same time.
noun
a message posted to two or more message boards or electronic mailing lists at the same time: Cross-posts are often greeted with hostility.