3 # checkmail Version 0.6.1 by Thomas Hochstein
5 # This script tries to verify the deliverability of (a) mail address(es).
7 # Copyright (c) 2002-2011 Thomas Hochstein <thh@inter.net>
9 # It can be redistributed and/or modified under the same terms under
10 # which Perl itself is published.
12 our $VERSION = "0.6.2";
14 ################################# Configuration ################################
15 # Please fill in a working configuration!
17 # value used for HELO/EHLO - a valid hostname you own
18 helo => 'testhost.domain.example',
19 # value used for MAIL FROM: - a valid address under your control
20 from => 'mailtest@testhost.domain.example'
23 ################################### Modules ####################################
31 ################################# Main program #################################
33 $Getopt::Std::STANDARD_HELP_VERSION = 1;
34 my $myself = basename($0);
36 # read commandline options
38 getopts('Vhqlrf:m:s:e:', \%options);
42 print "$myself v $VERSION\nCopyright (c) 2010-2016 Thomas Hochstein <thh\@inter.net>\n";
43 print "This program is free software; you may redistribute it and/or modify it under the same terms as Perl itself.\n";
47 # -h: feed myself to perldoc
53 # display usage information if neither -f nor an address are present
54 if (!$options{'f'} and !$ARGV[0]) {
55 print "Usage: $myself [-hqlr] [-m <host>] [-s <from>] [-e <EHLO>] <address>|-f <file>\n";
56 print "Options: -V display copyright and version\n";
57 print " -h show documentation\n";
58 print " -q quiet (no output, just exit with 0/1/2/3)\n";
59 print " -l extended logging\n";
60 print " -r test random address to verify verification\n";
61 print " -m <host> no DNS lookup, just test this host\n";
62 print " -s <from> override configured value for MAIL FROM\n";
63 print " -e <EHLO> override configured value for EHLO\n";
64 print " <address> mail address to check\n\n";
65 print " -f <file> parse file (one address per line)\n";
69 # -s / -e: override configuration
70 $config{'from'} = $options{'s'} if defined($options{'s'});
71 $config{'helo'} = $options{'e'} if $options{'e'};
73 # -f: open file and read addresses to @adresses
76 if (-e $options{'f'}) {
77 open FILE, "<$options{'f'}" or die("$myself ERROR: Could not open file $options{'f'} for reading: $!");
79 die("$myself ERROR: File $options{'f'} does not exist!\n");
86 # fill @adresses with single address to check
88 push(@addresses,$ARGV[0]);
91 # loop over each address and test it
92 my (%targets,$curstat,$status,$log,$message);
93 foreach (@addresses) {
95 # regexp taken from http://www.regular-expressions.info/email.html
96 # with escaping of "/" added two times and "*" changed to "+"
97 # in localpart, second alternative
98 if ($address !~ /^(?:[a-z0-9!#$%&'*+\/=?^_`{|}~-]+(?:\.[a-z0-9!#$%&'*+\/=?^_`{|}~-]+)*|"(?:[\x01-\x08\x0b\x0c\x0e-\x1f\x21\x23-\x5b\x5d-\x7f]|\\[\x01-\x09\x0b\x0c\x0e-\x7f]+)")@(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?$/i) {
99 printf(" > Address <%s> is syntactically INVALID.\n",$address) if !($options{'q'});
102 my $domain = Mail::Address->new('',$address)->host;
103 printf(" * Testing %s ...\n",$address) if !($options{'q'});
104 $log .= "\n===== BEGIN $address =====\n";
105 # get list of target hosts or take host forced via -m
106 if (!$options{'m'}) {
107 %targets = %{gettargets($domain,\$log)};
109 $message = sprintf("Connection to %s forced by -m.\n",$options{'m'});
111 print " $message" if !($options{'q'});
112 # just one target host with preference 0
113 $targets{$options{'m'}} = 0;
116 $curstat = checkaddress($address,\%targets,\$log);
119 $message = 'DNS lookup failure';
120 printf(" > Address is INVALID (%s).\n",$message) if !($options{'q'});
121 $log .= $message . '.';
123 $log .= "====== END $address ======\n";
125 $status = $curstat if (!defined($status) or $curstat > $status);
128 print $log if ($options{'l'});
130 # status 0: valid / batch processing
131 # 1: connection failed or temporary failure
134 #D print "\n-> EXIT $status\n";
137 ################################## gettargets ##################################
138 # get mail exchanger(s) or A record(s) for a domain
139 # IN : $domain: domain to query the DNS for
140 # OUT: \%targets: reference to a hash containing a list of target hosts
142 my ($domain,$logr) = @_;
144 my $resolver = Net::DNS::Resolver->new(udp_timeout => 15, tcp_timeout => 15);
147 # get MX record(s) as a list sorted by preference
148 if (my @mxrr = mx($resolver,$domain)) {
149 print_dns_result($domain,'MX',scalar(@mxrr),undef,$logr);
150 foreach my $rr (@mxrr) {
151 $targets{$rr->exchange} = $rr->preference;
152 $$logr .= sprintf("(%d) %s\n",$rr->preference,$rr->exchange);
154 # no MX record found; log and try A record(s)
156 print_dns_result($domain,'MX',undef,$resolver->errorstring,$logr);
157 print(" Falling back to A record ...\n") if !($options{'q'});
159 if (my $query = $resolver->query($domain,'A','IN')) {
160 print_dns_result($domain,'A',$query->header->ancount,undef,$logr);
161 foreach my $rr ($query->answer) {
162 $targets{$rr->address} = 0;
163 $$logr .= sprintf("- %s\n",$rr->address);
165 # no A record found either; log and fail
167 print_dns_result($domain,'A',undef,$resolver->errorstring,$logr);
168 printf(" %s has neither MX nor A records - mail cannot be delivered.\n",$domain) if !($options{'q'});
174 ################################# checkaddress #################################
175 # test address for deliverability
176 # IN : $address: adress to be tested
177 # \%targets: reference to a hash containing a list of MX hosts
178 # \$log : reference to the log (to be printed out via -l)
180 # \$log will be changed
182 my ($address,$targetsr,$logr) = @_;
183 my %targets = %{$targetsr};
185 # walk %targets in order of preference
186 foreach my $host (sort { $targets{$a} <=> $targets{$b} } keys %targets) {
187 printf(" / Trying %s (%s) with %s\n",$host,$targets{$host} || 'A',$address) if !($options{'q'});
188 $$logr .= sprintf("%s:\n%s\n",$host,"-" x (length($host)+1));
189 $status = checksmtp($address,$host,$logr);
190 last if ($status != 1);
195 ################################### checksmtp ##################################
196 # connect to a remote machine on port 25 and test deliverability of a mail
197 # address by doing the SMTP dialog until RCPT TO stage
198 # IN : $address: address to test
199 # $target : target host
200 # \$log : reference to the log (to be printed out via -l)
201 # OUT: .........: reference to a hash containing a list of target hosts
202 # \$log will be changed
204 my ($address,$target,$logr) = @_;
206 # start SMTP connection
207 if (my $smtp = Net::SMTP->new($target,Hello => $config{'helo'},Timeout => 30)) {
208 $$logr .= $smtp->banner; # Net::SMTP doesn't seem to support multiline greetings.
209 $$logr .= "EHLO $config{'helo'}\n";
210 log_smtp_reply($logr,$smtp->code,$smtp->message);
211 $smtp->mail($config{'from'});
212 $$logr .= "MAIL FROM:<$config{'from'}>\n";
213 log_smtp_reply($logr,$smtp->code,$smtp->message);
215 my ($success,$code,@message) = try_rcpt_to(\$smtp,$address,$logr);
216 # connection failure?
218 $status = connection_failed(@message);
219 # delivery attempt was successful?
221 # -r: try random address (which should be guaranteed to be invalid)
223 my ($success,$code,@message) = try_rcpt_to(\$smtp,create_rand_addr(Mail::Address->new('',$address)->host),$logr);
224 # connection failure?
226 $status = connection_failed(@message);
227 # reset status - the address has been checked and _is_ valid!
229 print " > Address verification currently impossible. You'll have to try again or send a test mail ...\n" if !($options{'q'});
230 # verification impossible?
233 print " > Address verification impossible. You'll have to send a test mail ...\n" if !($options{'q'});
236 # if -r is not set or status was not set to 3: valid address
237 if (!defined($status)) {
239 print " > Address is valid.\n" if !($options{'q'});
241 # delivery attempt failed?
244 print " > Address is INVALID:\n" if !($options{'q'});
245 print ' ' . join(' ',@message) if !($options{'q'});
247 # terminate SMTP connection
250 log_smtp_reply($logr,$smtp->code,$smtp->message);
252 # SMTP connection failed / timeout
253 $status = connection_failed();
254 $$logr .= "---Connection failure---\n";
259 ############################### create_rand_addr ###############################
260 # create a random mail address
261 # IN : $domain: the domain part
262 # OUT: $address: the address
263 sub create_rand_addr {
265 my $allowed = 'ABCDEFGHJKLMNPQRSTUVWXYZabcdefghjkmnpqrstuvwxyz23456789-+_=';
267 while (length($address) < 15) {
268 $address .= substr($allowed, (int(rand(length($allowed)))),1);
270 return ($address.'@'.$domain);
273 ################################ parse_dns_reply ###############################
274 # parse DNS response codes and return code and description
275 # IN : $response: a DNS response code
276 # OUT: "$response ($desciption)"
277 sub parse_dns_reply {
279 my %dnsrespcodes = (NOERROR => 'empty response',
280 NXDOMAIN => 'non-existent domain',
281 SERVFAIL => 'DNS server failure',
282 REFUSED => 'DNS query refused',
283 FORMERR => 'format error',
284 NOTIMP => 'not implemented');
285 if(defined($dnsrespcodes{$response})) {
286 return sprintf('%s (%s)',$response,$dnsrespcodes{$response});
292 ############################### print_dns_result ###############################
293 # print and log result of DNS query
294 # IN : $domain: domain the DNS was queried for
295 # $type : record type (MX, A, ...)
296 # $count : number of records found
297 # $error : DNS response code
298 # \$log : reference to the log (to be printed out via -l)
300 # \$log will be changed
301 sub print_dns_result {
302 my ($domain,$type,$count,$error,$logr) = @_;
303 if (defined($count)) {
304 printf(" %d %s record(s) found for %s\n",$count,$type,$domain) if !($options{'q'});
305 $$logr .= sprintf("%s DNS record(s):\n",$type);
307 printf(" No %s records found for %s: %s\n",$type,$domain,parse_dns_reply($error)) if !($options{'q'});
308 $$logr .= sprintf("No %s records found: %s\n",$type,parse_dns_reply($error));
313 ################################## try_rcpt_to #################################
314 # send RCPT TO and return replies
315 # IN : \$smtp : a reference to an SMTP object
316 # $recipient: a mail address
317 # \$log : reference to the log (to be printed out via -l)
318 # OUT: $success: exit code (0 for false, 1 for true, -1 for tempfail)
319 # $code : SMTP status code
320 # $message: SMTP status message
321 # \$log will be changed
323 my($smtpr,$recipient,$logr)=@_;
324 $$logr .= sprintf("RCPT TO:<%s>\n",$recipient);
326 $$smtpr->to($recipient);
328 log_smtp_reply($logr,$$smtpr->code,$$smtpr->message);
329 $success = analyze_smtp_reply($$smtpr->code,$$smtpr->message);
332 $$logr .= "---Connection failure---\n";
334 return ($success,$$smtpr->code,$$smtpr->message);
337 ################################ log_smtp_reply ################################
338 # log result of SMTP command
339 # IN : \$log : reference to the log (to be printed out via -l)
340 # $code : SMTP status code
341 # @message : SMTP status message
343 # \$log will be changed
345 my($logr,$code,@message)=@_;
346 $$logr .= sprintf('%s %s',$code,join('- ',@message));
350 ############################### analyze_smtp_reply ##############################
351 # analyze SMTP response codes and messages
352 # IN : $code : SMTP status code
353 # @message : SMTP status message
354 # OUT: exit code (0 for false, 1 for true, -1 for tempfail)
355 sub analyze_smtp_reply {
356 my($code,@message)=@_;
357 my $type = substr($code, 0, 1);
360 } elsif ($type == 5) {
362 } elsif ($type == 4) {
368 ############################## connection_failed ###############################
369 # print failure message and return status 1
370 # IN : @message : SMTP status message
372 sub connection_failed {
374 print " ! Connection failed or other temporary failure.\n" if !($options{'q'});
375 printf(" %s\n",join(' ',@message)) if @message;
381 ################################ Documentation #################################
385 checkmail - check deliverability of a mail address
389 B<checkmail> [B<-Vhqlr>] [B<-m> I<host>] [-s I<sender>] [-e I<EHLO>] I<address>|B<-f> I<file>
409 Mail::Address I<(CPAN)>
421 Furthermore you'll need a working DNS installation.
425 checkmail checks the vailidity / deliverability of a mail address.
426 You may submit just one address as the last argument or a file
427 containing one address on each line using the B<-f> option.
431 For the time being, all configuration is done in the script. You have
432 to set the following elements of the %config hash:
436 =item B<$config{'helo'}>
438 The hostname to be used for I<HELO> or I<EHLO> in the SMTP dialog.
440 =item B<$config{'from'}>
442 The sender address to be used for I<MAIL FROM> while testing.
443 May be empty ('') to set '<>' as MAIL FROM.
447 You may override that configuration by using the B<-e> and B<-s>
448 command line options.
452 After configuring the script you may run your first test with
454 checkmail user@example.org
456 B<checkmail> will check the address for syntactic validity. If the
457 address is valid, it will try to determine the mail exchanger(s) (MX)
458 responsible for I<example.org> by querying the DNS for the respective
459 MX records and then try to connect via SMTP (on port 25) to each of
460 them in order of precedence (if necessary). It will run through the
461 SMTP dialog until just before the I<DATA> stage, i.e. doing I<EHLO>,
462 I<MAIL FROM> and I<RCPT TO>. If no MX is defined, B<checkmail> will
463 fall back to the I<example.org> host itself, provided there is at
464 least one A record defined in the DNS. If there are neither MX nor A
465 records for I<example.org>, mail is not deliverable and B<checkmail>
466 will fail accordingly. If no host can be reached, B<checkmail> will
467 fail, too. Finally B<checkmail> will fail if mail to the given
468 recipient is not accepted by the respective host.
470 If B<checkmail> fails, you'll not be able to deliver mail to that
471 address - at least not using the configured sender address and from
472 the host you're testing from. However, the opposite is not true: a
473 mail you send may still not be delivered even if a test via
474 B<checkmail> succeeds. The receiving entity may reject your mail after
475 the I<DATA> stage, due to content checking or without any special
476 reason, or it may even drop, filter or bounce your mail after finally
477 accepting it. There is no way to be sure a mail will be accepted short
478 of sending a real mail to the address in question.
480 You may, however, try to detect hosts that will happily accept any and
481 all recipient in the SMTP dialog and just reject your mail later on,
482 for example to defeat exactly the kind of check you try to do.
483 B<checkmail> will do that by submitting a recipient address that is
484 known to be invalid; if that address is accepted, too, you'll know
485 that you can't reliably check the validity of any address on that
486 host. You can force that check by using the B<-r> option.
488 If you don't want to see just the results of your test, you can get a
489 B<complete log> of the SMTP dialog by using the B<-l> option. That may be
490 helpful to test for temporary failure conditions.
492 On the other hand you may use the B<-q> option to suppress all output;
493 B<checkmail> will then terminate with one of the following B<exit
500 address(es) seem/seems to be valid
504 temporary error (connection failure or temporary failure)
512 address cannot reliably be checked (test using B<-r> failed)
516 You can do B<batch processing> using B<-f> and submitting a file with
517 one address on each line. In that case the exit status is set to the
518 highest value generated by testing all addresses, i.e. it is set to
519 B<0> if and only if no adress failed, but to B<2> if even one address
520 failed and to B<3> if even one addresses couldn't reliably be checked.
522 And finally you can B<suppress DNS lookups> for MX and A records and
523 just force B<checkmail> to connect to a particular host using the
526 B<Please note:> You shouldn't try to validate addresses while working
527 from a dial-up or blacklisted host. If in doubt, use the B<-l> option
528 to have a closer look on the SMTP dialog yourself.
530 B<Please note:> To avoid shell expansion on addresses you submit to
531 B<checkmail>, use B<batch processing>.
537 =item B<-V> (version)
539 Print out version and copyright information on B<checkmail> and exit.
543 Print this man page and exit.
547 Suppress output and just terminate with a specific exit status.
551 Log and print out the whole SMTP dialog.
553 =item B<-r> (random address)
555 Also try a reliably invalid address to catch hosts that try undermine
556 address verification.
558 =item B<-m> I<host> (MX to use)
560 Force a connection to I<host> to check deliverability to that
561 particular host irrespective of DNS entries. For example:
563 checkmail -m test.host.example user@domain.example
565 =item B<-s> I<sender> (value for MAIL FROM)
567 Override configuration and use I<sender> for MAIL FROM.
569 =item B<-e> I<EHLO> (value for EHLO)
571 Override configuration and use I<EHLO> for EHLO.
573 =item B<-f> I<file> (file)
575 Process all addresses from I<file> (one on each line).
581 Just copy checkmail to some directory and get started.
583 You can run your first test with
585 checkmail user@example.org
589 See documentation of I<Net::DNS::Resolver>.
595 =item F<checkmail.pl>
603 Please report any bugs or feature request to the author or use the
604 bug tracker at L<http://bugs.th-h.de/>!
608 L<http://th-h.de/download/scripts.php> will have the current
609 version of this program.
611 This program is maintained using the Git version control system. You
612 may clone L<git://code.th-h.de/mail/checkmail.git> to check out the
613 current development tree or browse it on the web via
614 L<http://code.th-h.de/?p=mail/checkmail.git>.
618 Thomas Hochstein <thh@inter.net>
620 =head1 COPYRIGHT AND LICENSE
622 Copyright (c) 2002-2010 Thomas Hochstein <thh@inter.net>
624 This program is free software; you may redistribute it and/or modify it
625 under the same terms as Perl itself.