Ensure that your email address is professional -- use your name, or your business' name rather than something like "firstname.lastname@example.org." You need people to take you seriously, but if they receive an email from an address like the one above, then they will disregard anything you have to say, no matter how intelligent it might be.
The domain you use to host your email is just as important. Users who cling to Hotmail, Yahoo or Verizon email addresses send a message that they are not necessarily Internet-savvy and are unwilling to adapt to modern technology. Stick to domains that are associated with your business to prove your professionalism.
Last impressions are just as important as first, so you have to ensure your email signature represents your brand well and proves you are credible in your industry. Keep things simple; you don't need large, colorful fonts and inspirational quotes, nor do you need to list all your credentials along with your graduation dates. A great way to build on opportunity in your email signature is to add links to social media pages, blogs and websites with a call to action like "Visit me," or "Check us out." Just remember not to overdo it.
Remember that your brand is represented in everything you do, including every single email you send. Be professional, show people what your company is about, and keep things short and sweet.
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(Photo credit: Seth MacEntee