So much marketing email is written in the dreadful "Hi, I'm a corporation!" voice. Apart from being a bit painful to read, it blows a big opportunity to make a connection with the recipient and thereby increase the chances that they will respond in some way (for example, visiting your site, making a purchase, signing up for your event). That's the point that Nick Usborne makes in a MarketingProfs piece in which he offers some very simple suggestions on how to humanize your email messages.
(You have to be a premium member to read it - and being a premium members is worth it! MarketingProfs specializes in this handy pieces that give you some great tips you can put into use immediately, and you're bound to find a couple of worthwhile webinars out of their packed schedule... my big complaint is that I just can't participate in as many as I want. I recommend it.)
The tips are straightforward: write in a one-on-one style. Make sure the message comes from a real person, whose name is in the body and on the headers. And include contact information.
That last one is a pet peeve of mine; nothing will make me less interested in doing business with you than getting an email from a "send-only" mailbox. If you are going to email me, be ready for me to email you back. So many companies do this, and it's like calling a customer on the phone and then saying "Wait! Don't talk to me! This is a one way phone line!" Dumb, dumb, dumb.
If your email volume is high enough that this seems unmanageable, invest in software that will analyze inbound messages and take a first pass at classifying them or auto-responding with helpful information. (I am not annoyed when I get a message that says, "We think this might answer your question, but if not, just reply again and someone will get back to you." That's just a good time-saver for everybody.)
Nick's tips are great and if you're not doing these things already, you should start with your next email campaign.