Don't post just to raise your post count, there is no bonus in it, and moderators will become frustrated with the spam. Continued post spamming will result in a suitable sanction.
Although it's not explicitly against the rules, I think the notion that spam is bad is pretty implicit.
That said, many people don't use the "View New Content" button, so they don't even notice it's happening and I can accept that you're only annoyed, not genuinely on the brink of genocide.
On a personal note though, I think welcoming so many people in the same space of time with the same generic message kinda causes the meaning to get lost....