直貼りしていいのかわからないけど
ググったらこんなに出てきた
どれかあるといいね

ftp://ftp.highway1.com.au/pub/FreeBSD/i368/5.1-RELEASE/packages/All/fetchmail-6.2.0.tbz
ftp://ftp.cse.buffalo.edu/mirror/BSD/FreeBSD-Archive/ports/i386/packages-5.1-release/All/fetchmail-6.2.0.tbz
ftp://ftp.cronyx.ru/pub/FreeBSD.archive/old-releases/i386/5.1-RELEASE/packages/All/fetchmail-6.2.0.tbz
ftp://195.208.247.18/pub/FreeBSD/5.1-RELEASE/packages/All/fetchmail-6.2.0.tbz
ftp://195.208.248.42/pub/FreeBSD/5.1-RELEASE/packages/All/fetchmail-6.2.0.tbz
ftp://ftp.mtu.ru/.3/FreeBSD-Archive/i386/5.1-RELEASE/packages/All/fetchmail-6.2.0.tbz
ftp://194.67.80.52/.3/FreeBSD-Archive/ports/i386/packages-5.1-release/All/fetchmail-6.2.0.tbz
ftp://213.24.208.27/.3/FreeBSD-Archive/ports/i386/packages-5.1-release/All/fetchmail-6.2.0.tbz
ftp://194.186.254.27/.3/FreeBSD-Archive/ports/i386/packages-5.1-release/All/fetchmail-6.2.0.tbz
ftp://ftp.mtu.ru/.2/FreeBSD-Archive/i386/i386/5.1-RELEASE/packages/All/fetchmail-6.2.0.tbz