$server_name =~ m{
    \A                   # start of string
    .{1,3}               # 1-3 characters
    \.                   # a literal period
    product1help\.com    # literal 'product1help.com'
}xms;

##</code><code>##

$server_name =~ m{
    \A                   # start of string
    (                    # start capture 1
        .{1,3}           # 1-3 characters
    )                    # end capture 1
    \.                   # a literal period
    product1help\.com    # literal 'product1help.com'
}xms;
my $prefix = $1;