After looking at Reputation and Recognition, Day three of "The Five Rs of Email" has us looking at Readability.
According to the Wikipedia "Readability is defined as reading ease, especially as it results from a writing style… In the reader, those features affecting readability are 1. prior knowledge, 2. reading skill, 3. interest, and 4. motivation. In the text, those features are 1. content, 2. style, 3. design, and 4. structure"
Lets start by answering these these two questions;
1 – How easy is your message to read?

Messages should be engaging and easy to read, something that everyone will understand and that is tailored to your audience.  Using an overlay or mapping tool to locate hotspots in your messaging is also something that will provide insight and understanding into how your members are interacting with your messages.  

2 – Is this the proper tone for my readers?
A message directed to a the average B2B list should use the appropriate business terms, definitions and tone as expected when dealing with users.  Respecting the length of your messages and the number of images being displayed in a corporate environment should also be considered when developing your messages. These messages should have the expectation that your target audince know their business and the terms commonly used within the industry.  Messages should provide Relevance, expand sector knowledge, save time and help the ever important botton line. 
While communications from a consumer service industry can and probably should be slightly more relaxed with their communications…  for example; L33t speak may be appropriate if your targeting gamers.  Knowing your audience and speaking their "language" will help them relate with your brand and build a Relationship with your brand.
Don't alienate your readers with language that is unsuitable for your brand, or the audience your trying to reach.  Relate to them and they will reward you with loyalty and interactions.