You can get everything right, and be tripped up by the minutia.
Compare, for example, these two approaches:
My name is Richard Millington, I'm the community manager for CoinCrazy.
CoinCrazy is an organization that sells rare coins to passionate collectors like yourself. As part of our mission, we have recently created a community for people that are passionate about rare coins.
This is going to be a place where you can get up-to-date information about where to buy rare coins, discuss your love of coins with your friends, and get expert advice about how to present the coins you have collected.
We would love you to become one of the first members of our new CoinCrazy community. As a first member you would get a unique badge you can display in your online profiles, the latest information about your upcoming CoinTrade events and be able to give your ideas on how the community should be developed.
You can sign up here: www.coincrazyurl.com
Thank you for your time,
CoinCrazy Community Manager
The CoinCrazy Organization
This style of approach, with a wide variety of spacing/font issues, is very common. It's driven by marketing teams. It lacks the empathy with the people you're trying to reach and displays a complete lack of personality. It's also far too long. These sorts of approaches rarely get a big response.
The people you're trying to reach don't want to feel like interchangable cogs. They want to feel appreciated for the skills/knowledge/resources/attributes they believe they have. They want to be able to put these to good use. Your approach needs to recognise this.
I loved what you wrote about the Kennedy coin on CoinCollector last week.
Do you feel that the reason these coins never became so popular was because they were so mass-produced?
I also noticed in your profile that you love the late 50s coins. Is this an area of expertise? I'm about to launch a community for coin lovers and I'm looking for someone that has a unique expertise in 50s coins.
Would you be interested in being involved?
The questions are just examples. Notice the personalisation of the e-mail. Notice that it asks questions based upon someone's previous contributions. Notice it recognises and gives appreciation for someone's expertise. Notice the length of the e-mail. Notice the lack of an in-depth explanation about the company I work for.
The goal is simply to spike an interest and gain an initial commitment from which we can further build a relationship.
This is just one example. You can adapt/tailor to see your fit. It's the minutia of your interactions with members that matter. If you sound too formal, your response rate plummets.
You can research your target audience, highlight common topics of interest, identify their biggest problem, look up details specific to the person you're trying to reach, discover their e-mail address, and then…after all this…screw up the e-mail by being slightly more formal.
It's a simple thing to fix, it just takes a little more time and effort.