Title: Checking valid e-mail address in the easy way
Submitter: Not specified Not specified (other recipes)
Last Updated: 2001/09/23
Version no: 1.0
Category:

Description:

This code Perl snipet is intended to check valid e-mail address, code is easy to understand because composed by step by step regex rather than full one line complicated regex, thus its makes each step may be easily modified as needed.

Contact me: tbyte@bolehmail.com

Usage: Text Source

sub ValidEmailAddr { #check if e-mail address format is valid

  my $mail = shift;                                                  #in form name@host

  return 0 if ( $mail !~ /^[0-9a-zA-Z\.\-\_]+\@[0-9a-zA-Z\.\-]+$/ ); #characters allowed on name: 0-9a-Z-._ on host: 0-9a-Z-. on between: @

  return 0 if ( $mail =~ /^[^0-9a-zA-Z]|[^0-9a-zA-Z]$/);             #must start or end with alpha or num

  return 0 if ( $mail !~ /([0-9a-zA-Z]{1})\@./ );                    #name must end with alpha or num

  return 0 if ( $mail !~ /.\@([0-9a-zA-Z]{1})/ );                    #host must start with alpha or num

  return 0 if ( $mail =~ /.\.\-.|.\-\..|.\.\..|.\-\-./g );           #pair .- or -. or -- or .. not allowed

  return 0 if ( $mail =~ /.\.\_.|.\-\_.|.\_\..|.\_\-.|.\_\_./g );    #pair ._ or -_ or _. or _- or __ not allowed

  return 0 if ( $mail !~ /\.([a-zA-Z]{2,3})$/ );                     #host must end with '.' plus 2 or 3 alpha for TopLevelDomain (MUST be modified in future!)

  return 1;
}

The license for this recipe is available here.

Discussion:

As ICANN already assigned Top Level Domain name more than 3 characters, user must be modified the last code fragment.