#!/bin/awk -f
/^[Xx]-[Mm]ailer:/	{
			gotheader=1
			mailer=$0
		}
/^[Xx]-[Mm][Ii][Mm][Ee]OLE:/	{
			if (gotheader!=1) { mailer=$0}
		}
/^[Uu]ser-[Aa]gent:/	{
			mailer=$0
		}
END		{
			print mailer
		}