title: How to create Gmail filter searching for text only at start of subject line?
body: <p>We receive regular automated build messages from Jenkins build servers at work.</p>
  
  <p>It'd be nice to ferret these away into a label, skipping the inbox.</p>
  
  <p>Using a filter is of course the right choice.</p>
  
  <p>The desired identifier is the string <code>[RELEASE]</code> at the beginning of a subject line.</p>
  
  <p>Attempting to specify any of the following regexes causes emails with the string <code>release</code> in any case anywhere in the subject line to be matched:</p>
  
  <pre><code>\[RELEASE\]*
  ^\[RELEASE\]
  ^\[RELEASE\]*
  ^\[RELEASE\].*
  </code></pre>
  
  <p>From what I've read subsequently, Gmail doesn't have standard regex support, and from experimentation it seems, as with google search, special characters are simply ignored. </p>
  
  <p>I'm therefore looking for a search parameter which can be used, maybe something like <code>atstart:mystring</code> in keeping with their <code>has:</code>, <code>in:</code> notations.</p>
  
  <p>Is there a way to force the match only if it occurs at the start of the line, and only in the case where square brackets are included?</p>
  
  <p>Sincere thanks.</p>