I just figured I'd give my thoughts on the people asking about contacting the employer too much. When people reach out to me, I do get back to them, but your email is absolutely the lowest priority thing I have to do. It can sometimes take a while, so I think when you do that initial out reach, let the person know you don't expect an immediate response, you have a long term interest, and you want to hear back whenever the person has the time, even if it is a few months from now.
I know that sucks, but for the busier recruiting/hiring people, but the time they get to an email after a few weeks/months, they likely just assume the person moved on.
On the flip side of that, you can definitely annoy hiring people by following up too often. If the company means that much to you that you are willing to risk a "black mark" by following up a second time just to get a response to your inquiry, go for it. Otherwise, I recommend waiting to follow up until you have something to add, like, "hi, I applied for this position a few months ago. I recently added X skill or took Y course and I feel like it would be really useful to your company for Z reason. I've updated my application to reflect this new information. I want to work with your company because W reason and will always be available to talk about the possibility with you." That would be enough to make me at least revisit your materials to see how things look.
