Always use use strict; use warnings;! 

my $line = "mail: asdf@123.com";

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should be 
my $line = 'mail: asdf@123.com';

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Then you can simply use 

if (my ($mail) = $line =~ /mail: (.*)/) {
    print "mail=$mail\n";
}

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In reply to Re: Problem with ampersand and regex by ikegami
in thread Problem with ampersand and regex by Anonymous Monk

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