Description:
------------
when mail() is passing the headers to get the sender's email address and the headers are similar to the following:
  To: blah
  From: user@domain.tld
  AnotherHeader: value
it retrieves " user@domain.tld" as the senders email, instead of "user@domain.tld".  this is a problem when sending email to yahoo, as the MAIL FROM smtp command that mail() generates looks like the following:
  MAIL FROM:< user@domain.tld>
instead of 
  MAIL FROM:<user@domain.tld>
or
  MAIL FROM: <user@domain.tld>
and yahoo rejects.


Reproduce code:
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mail('test@yahoo.com','test subject','test body','From: user@myserver.tld');

Expected result:
----------------
yahoo rejects with the following
  501 Syntax error in parameters or arguments


Actual result:
--------------
n/a