Simple method to sort versions

SortBy[ 
 PadRight[#, 3] & @* StringCases[n : DigitCharacter .. :> ToExpression[n]]
] @ versions // Reverse

versions[[Ordering @ - PadRight@ToExpression[Rest /@ StringSplit[versions, "@" | "."]]]]

{"[email protected]", "[email protected]", "[email protected]", "[email protected]", "[email protected]", "[email protected]", "[email protected]"}

Reverse@SortBy[
 versions, 
 PadRight[ToExpression[
  StringSplit[StringDrop[#, StringPosition[#, "@"][[-1, 1]]], "."]],
  3] &
]

{"[email protected]", "[email protected]", "[email protected]", "[email protected]", "[email protected]", "[email protected]", "[email protected]"}