I use Regexp::Common

use Regexp::Common qw[Email::Address];

unless ($email_addr =~ m/($RE{Email}{Address})/) {
  # error
}
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I also just started using Email::Valid. It can do checks to see if the domain really exists and has a MX record.

unless (Email::Valid->address(-address => $email_addr, -mxcheck => 1))
+ {
  # error
}
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