Internet Message Format (IMF) is specified by RFC 5322. It defines a variety of header fields, such as To, From, and Subject.

It also defines the Comments header field and the Keywords header field.


Does anything actually use these two header fields today, or are they totally superfulous? In other words, are mail clients in modern use expected to make use of these?

  • I'm not sure what actual problem you are facing? Nov 14, 2012 at 21:33
  • 1
    Pretty simple: Comments and Keywords are header available to email clients and servers. As far as I can tell, none of my clients use them. I am wondering if any clients or servers actually use them. Nov 15, 2012 at 14:19
  • 2
    I'm not sure why this is considered "not constructive". I'm very curious to know the answer, and answers would certainly be supported by facts and references.
    – npdoty
    Nov 21, 2013 at 22:03
  • Closers can be trigger happy. It happens. Nov 21, 2013 at 23:27
  • Made edit to more literally meet SO requirements. Dec 28, 2016 at 16:00


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