[[!comment format=mdwn
 username="ewen"
 avatar="http://cdn.libravatar.org/avatar/605b2981cb52b4af268455dee7a4f64e"
 subject="User-Agent"
 date="2018-07-15T02:21:47Z"
 content="""
In theory `User-Agent:` is \"optional\", but [clients `SHOULD` send it](https://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.43).  Looks like some servers are particularly fussy about it being sent... and off the top of my head I can't think of a reason *not* to send a `User-Agent:` header of some sort, as it is *very* widely sent.

Ewen
"""]]
