cross-posting
noun [ C or U ]
ukus COMMUNICATIONS, INTERNET
the act of sending a message to more than one internet discussion group or news group at a time, or the message that is sent:
Cross-posting should be limited to a small number of directly related groups.
We do not accept cross-postings unless they are to highly appropriate groups.
cross-post
verb [ I or T ]
Please, only cross-post if you are sure your article is suitable for the different newsgroups.