title: Is it correct that sometimes I get angle brackets in "From" field of an e-mail message?
body: <p>My software is working with incoming e-mail from the one and only particular sender (let it be SantaClaus@hetnet.nl). According to RFC-2616 section 14 "From" header </p>
  
  <blockquote>
    <p>MAY be used for logging purposes and
    <strong>as a means for identifying the source of invalid or unwanted
    requests.</strong></p>
  </blockquote>
  
  <p>That's exactly what I needed, so I wrote a code, which ignores all  the messages where "From" field doesn't equal <code>SantaClaus@hetnet.nl</code>. It worked good, but one day things changed, and now all the messages form Santa Claus contains a different string in "From" field (exactly <code>&lt;SantaClaus@hetnet.nl&gt;</code>). 
  I already fixed my code, but I just wonder, is this header legal? Because the same RFC-2616 section 14 says: </p>
  
  <blockquote>
    <p>The address SHOULD be machine-usable,
    as defined by "mailbox" in RFC 822 [9]
    as updated by RFC 1123 [8]:</p>
  
  <pre><code>   From   = "From" ":" mailbox
  </code></pre>
    
    <p>An example is:</p>
  
  <pre><code>   From: webmaster@w3.org
  </code></pre>
  </blockquote>
  
  <p>Note the absense of angle brackets. But at the same time, many e-mail messages I receive on my Gmail account has something like this in the "From" field: <code>"Santa Claus" &lt;santaclaus@hetnet.nl&gt;</code></p>