Possible unintended interpolation of %s in string

(W ambiguous) You said something like `@foo' in a double-quoted string but there was no array @foo in scope at the time. If you wanted a literal @foo, then write it as \@foo; otherwise find out what happened to the array you apparently lost track of.

@ now always interpolates an array in double-quotish strings.

print "To: someone@somewhere.com\n";

# perl4 prints: To:someone@somewhere.com
# perl < 5.6.1, error : In string, @somewhere now must be written as \
+@somewhere
# perl >= 5.6.1, warning : Possible unintended interpolation of @somew
+here in string
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