[Matthew.]

Necroposting
A necropost is a message that revives (as in necromancy) an arbitrarily old thread, causing it to appear above newer and more active threads. This practice is generally seen as a breach of netiquette on most forums.[citation needed] Because old threads are not usually locked from further posting, necroposting is common for newer users and in cases where the date of previous posts is not apparent.

Didn’t know that’s what it was called