aMSN has been replaced by amsn2 (currently available in amsn2-git). I suggest deleting all the amsn-* packages in [1] as most of them are orphaned, incompatible with amsn2 and most don't even build.
[1] https://aur.archlinux.org/packages/?O=0&C=0&SeB=nd&K=amsn&outdated=&SB=n&SO=a&PP=50&do_Search=Go J. Leclanche
