hi,
gibe-f (variante 1- microsoft) is catched by ms
but the second variante gibe-f  is only tagged as {dangerous-content}
sophos seems to be ok.
$ LANG=C sweep -mime -archive Announcement.eml
 >>> Virus 'W32/Gibe-F' found in file Announcement.eml/axria.exe
$ rpm -q mailscanner
mailscanner-4.26.8-1
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shrek-m