Simple past tense and past participle of crosspost.(verb)
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Use "crossposted" in a sentence
"Written by brebis noire, crossposted from the black ewe."
"This post is also crossposted at www. nclr.org/blog"
"Both stories show the effect of the collapsing of the mainstream media industry — the CBS story is crossposted by CNet. com reporter Declan McCullagh, the libertarian who fabricated the “Al Gore invented the Internet” story."