CUFILTER(1p) User Contributed Perl Documentation CUFILTER(1p)NAME
cufilter - Filter emails through Mail::CheckUser
SYNOPSIS
Add the following lines to your ~/.procmailrc:
# Filter mail through Mail::CheckUser
:0f
| /usr/bin/cufilter
DESCRIPTION
When email messages are filtered through this program using the procmail settings as outlined in the SYNOPSYS, the email address in the
"From:" header is passed through Mail::CheckUser to ensure validity. If there is a problem with the email address, the "Subject:" header
is modified to show which email address failed along with the failure reason. No messages are lost, but it provides an easy way for the
mail client to organize, sort, or filter based on the subject tweaks.
EXAMPLES
Lets say a spammer sends a message with the following headers:
From: god@heaven.org
To: you@host.com
Subject: Happy Pill
Then the new headers might change to the following:
From: god@heaven.org
To: you@host.com
Subject: [CU!god@heaven.org!DNS failure: SERVFAIL] Happy Pill
This makes it easy to filter for mail clients.
INSTALL
This file can be installed into /usr/bin/cufilter and is intended to be utilized through the procmail functionality by adding the following
lines to your ~/.procmailrc configuration.
# Filter mail through Mail::CheckUser
:0f
| /usr/bin/cufilter
AUTHORS
Rob Brown bbb@cpan.org
COPYRIGHT
Copyright (c) 2003 Rob Brown bbb@cpan.org. All rights reserved.
This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.
$Id: cufilter,v 1.3 2003/09/18 15:36:26 hookbot Exp $
SEE ALSO Mail::CheckUser(3), procmail(1).
perl v5.14.2 2012-03-10 CUFILTER(1p)
Check Out this Related Man Page
CheckUser(3pm) User Contributed Perl Documentation CheckUser(3pm)NAME
Mail::CheckUser - check email addresses for validity
SYNOPSIS
use Mail::CheckUser qw(check_email);
my $ok = check_email($email_addr);
use Mail::CheckUser qw(:constants check_email last_check)
my $ok = check_email($email_addr);
print "DNS timeout
"
if last_check()->{code} == CU_DNS_TIMEOUT;
use Mail::CheckUser;
my $res = Mail::CheckUser::check_email($email_addr);
DESCRIPTION
This Perl module provides routines for checking validity of email address.
It makes several checks:
1. It checks the syntax of an email address.
2. It checks if there any MX records or A records for the domain part of the email address.
3. It tries to connect to an email server directly via SMTP to check if mailbox is valid. Old versions of this module performed this
check via the VRFY command. Now the module uses another check; it uses a combination of MAIL and RCPT commands which simulates sending
an email. It can detect bad mailboxes in many cases.
If is possible to turn off some or all networking checks (items 2 and 3). See "GLOBAL VARIABLES".
This module was designed with CGIs (or any other dynamic Web content programmed with Perl) in mind. Usually it is required to quickly
check e-mail addresses in forms. If the check can't be finished in reasonable time, the e-mail address should be treated as valid. This
is the default policy. By default if a timeout happens the result of the check is treated as positive. This behavior can be overridden -
see "GLOBAL VARIABLES".
IMPORTANT WARNING
In many cases there is no way to detect the validity of email addresses with network checks. For example, non-monolithic mail servers
(such as Postfix and qmail) often report that a user exists even if it is not so. This is because in cases where the work of the server is
split among many components, the SMTP server may not know how to check for the existence of a particular user. Systems like these will
reject mail to unknown users, but they do so after the SMTP conversation. In cases like these, the only absolutely sure way to determine
whether or not a user exists is to actually send a mail and wait to see if a bounce messages comes back. Obviously, this is not a workable
strategy for this module. Does it mean that the network checks in this module are useless? No. For one thing, just the DNS checks go a
long way towards weeding out mistyped domain parts. Also, there are still many SMTP servers that will reject a bad address during the SMTP
conversation. Because of this, it's still a useful part of checking for a valid email address. And this module was designed such that if
there is exists possibility (however small) that the email address is valid, it will be treated as valid by this module.
Another warning is about $Mail::CheckUser::Treat_Timeout_As_Fail global variable. Use it carefully - if it is set to true then some valid
email addresses can be treated as bad simply because an SMTP or DNS server responds slowly.
Another warning is about $Mail::CheckUser::Treat_Full_As_Fail global variable. Use it carefully - if it is set to true then some valid
email addresses can be treated as bad simply because their mailbox happens to be temporarily full.
EXAMPLE
This simple script checks if email address "blabla@foo.bar" is valid.
use Mail::CheckUser qw(check_email last_check);
my $email = 'blabla@foo.bar';
if(check_email($email)) {
print "E-mail address <$email> is OK
";
} else {
print "E-mail address <$email> isn't valid: ",
last_check()->{reason}, "
";
}
SUBROUTINES
$ok = check_email($email)
Validates email address $email. Return true if email address is valid and false otherwise.
$res = last_check()
Returns detailed result of last check made with "check_email" as hash reference:
{ ok => OK, code => CODE, reason => REASON }
OK True if last checked email address is valid. False otherwise.
CODE
A number which describes result of last check. See "CONSTANTS".
REASON
A string which describes result of last check.
CONSTANTS
Constants used by "last_check" to describe result of last check can be exported with
use Mail::CheckUser qw(:constants)
List of all defined constants:
CU_OK
Check is successful.
CU_BAD_SYNTAX
Bad syntax of email address.
CU_UNKNOWN_DOMAIN
Mail domain mentioned in email address is unknown.
CU_DNS_TIMEOUT
Timeout has happen during DNS checks.
CU_UNKNOWN_USER
User is unknown on SMTP server.
CU_SMTP_TIMEOUT
Timeout has happen during SMTP checks.
CU_SMTP_UNREACHABLE
All SMTP servers for mail domain were found unreachable during SMTP checks.
CU_MAILBOX_FULL
Mailbox is temporarily full but probably a valid username.
GLOBAL VARIABLES
It is possible to configure "check_email" using the global variables listed below.
$Mail::CheckUser::Skip_Network_Checks
If true then do only syntax checks. By default it is false.
$Mail::CheckUser::Skip_SMTP_Checks
If it is true then do not try to connect to mail server to check if a user exists. If this is true, and
$Mail::CheckUser::Skip_Network_Checks is false, only syntax and DNS checks are performed. By default it is false.
$Mail::CheckUser::Skip_SYN
By default Net::Ping is used to determine remote reachability of SMTP servers before doing SMTP checks. Setting this to true skips
this check. By default it is false.
$Mail::CheckUser::Sender_Addr
MAIL/RCPT check needs an email address to use as the 'From' address when performing its checks. The default value is "check@user.com".
$Mail::CheckUser::Helo_Domain
Sender domain used in HELO SMTP command. If undef Net::SMTP is allowed to use its default value. By default it is undef.
Mail::CheckUser::Timeout
Timeout in seconds for network checks. By default it is 60.
$Mail::CheckUser::Treat_Timeout_As_Fail
If it is true "Mail::CheckUser" treats checks that time out as failed. By default it is false.
$Mail::CheckUser::Treat_Full_As_Fail
If it is true "Mail::CheckUser" treats error "552 mailbox full" as an invalid email and sets CU_MAILBOX_FULL. By default it is false.
$Mail::CheckUser::Net_DNS_Resolver
Override with customized Net::DNS::Resolver object. This is used to lookup MX and A records for the email domain when network checks
are enabled. If undef, Net::DNS::Resolver->new will be used. The default value is undef.
$Mail::CheckUser::Debug
If it is true then enable debug output on "STDERR". By default it is false.
AUTHORS
Ilya Martynov ilya@martynov.org
Rob Brown bbb@cpan.org
Module maintained at Source Forge ( http://sourceforge.net/projects/mail-checkuser/ ).
COPYRIGHT
Copyright (c) 1999-2003 by Ilya Martynov. All rights reserved.
This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.
$Id: CheckUser.pm,v 1.46 2003/09/18 23:51:36 hookbot Exp $
SEE ALSO perl(1).
perl v5.14.2 2012-03-10 CheckUser(3pm)