<p>Yes, some salutations and closings are <a href="https://meta.stackexchange.com/a/93989/150510">automatically removed</a> from new posts. </p>

<p>As Peter mentioned, there's no need to add a full signature since your gravatar automatically shows up in each of your post; feel free to put any additional information about you in your profile page. </p>

<p>Also, the SE system draws its strength from its wiki capabilities (<a href="http://www.codinghorror.com/blog/2008/04/introducing-stackoverflow-com.html" rel="nofollow noreferrer">and more</a>): unlike usual mailing-lists, greetings and thanks can be omitted since they are not an essential piece for building a live repository of good questions and answers. This does not mean that we are not courteous, just that we are aware that CV is a different place to ask questions. And rewarding existing answers by votes and green check can also be seen as a form of thanks.</p>
