diff --git a/lib/Email/Sender/Transport/SMTP.pm b/lib/Email/Sender/Transport/SMTP.pm
index 35a162b..79640bb 100644
--- a/lib/Email/Sender/Transport/SMTP.pm
+++ b/lib/Email/Sender/Transport/SMTP.pm
@@ -27,7 +27,9 @@ The following attributes may be passed to the constructor:
 
 =over 4
 
-=item C<host>: the name of the host to connect to; defaults to C<localhost>
+=item C<host>: the DNS name, IPv4 or IPv6 address of the host to connect to;
+ defaults to C<localhost>. Do not include a port number. Use the C<port>
+ option instead.
 
 =item C<ssl>: if 'starttls', use STARTTLS; if 'ssl' (or 1), connect securely;
 otherwise, no security
@@ -45,8 +47,10 @@ IO::Socket::SSL
 
 sub BUILD {
   my ($self) = @_;
-  Carp::croak("do not pass port number to SMTP transport in host, use port parameter")
-    if $self->host =~ /:/;
+  Carp::croak("Do not pass port number to SMTP transport in host, use port parameter")
+    if $self->host =~ /^\d+\.\d+\.\d+\.\d+:/			# IPv4 address
+    or $self->host =~ /^\[[\w:]{3,}\]:/					# IPv6 address
+    or $self->host =~ /^[\w\.]{3,}:/;					# DNS name
 }
 
 has host => (is => 'ro', isa => Str, default => sub { 'localhost' });
diff --git a/t/smtp-via-mock.t b/t/smtp-via-mock.t
index c546cf6..2968214 100644
--- a/t/smtp-via-mock.t
+++ b/t/smtp-via-mock.t
@@ -2,6 +2,7 @@
 use strict;
 use warnings;
 use Test::More;
+use Test::Exception;
 
 BEGIN {
 plan skip_all => 'Test::MockObject required to test SMTP transport by mocking'
@@ -32,7 +33,7 @@ BEGIN {
   $mock_smtp->{failaddr}{'permfail@example.net'} = [ 519 => 'Permanent STHU' ];
 }
 
-plan tests => 95;
+plan tests => 96;
 
 use Email::Sender::Transport::SMTP;
 use Email::Sender::Transport::SMTP::Persistent;
@@ -368,3 +369,45 @@ subtest "quoteaddr" => sub {
     is($q->(qq{$local\@example.com}), $want, "correct behavior for $local");
   }
 };
+
+subtest "portinaddr" => sub {
+  my @lives_tests = (
+    '1.1.1.1', 'IPv4 address',
+    '1::', 'IPv6 address 1 groups',
+    '1::8', 'IPv6 address 2 groups',
+    '1::ae:8', 'IPv6 address 3 groups',
+    '1::f45a:7:8', 'IPv6 address 4 groups',
+    '1::5:bd23:7:8', 'IPv6 address 5 groups',
+    '1::26fa:5:6:7:8', 'IPv6 address 6 groups',
+    '1::3:4:5:66ff:7:8', 'IPv6 address 7 groups',
+    '1:2:3:4:098a:6:7:8', 'IPv6 address 8 groups',
+    'server', 'Unqualified DNS name',
+    'corp.com', 'DNS zone',
+    'server.corp.com', 'Fully-qualified DNS name',
+  );
+  my @dies_tests = (
+    '1.1.1.1:125', 'IPv4 address with port',
+    '[::1]:125', 'IPv6 address shortest form with port',
+    '[1::]:125', 'IPv6 address 1 groups]:125',
+    '[1::8]:125', 'IPv6 address 2 groups]:125',
+    '[1::ae:8]:125', 'IPv6 address 3 groups]:125',
+    '[1::f45a:7:8]:125', 'IPv6 address 4 groups]:125',
+    '[1::5:bd23:7:8]:125', 'IPv6 address 5 groups]:125',
+    '[1::26fa:5:6:7:8]:125', 'IPv6 address 6 groups]:125',
+    '[1::3:4:5:66ff:7:8]:125', 'IPv6 address 7 groups]:125',
+    '[1:2:3:4:098a:6:7:8]:125', 'IPv6 address 8 groups]:125',
+    'server:125', 'Unqualified DNS name with port',
+    'corp.com:125', 'DNS zone with port',
+    'server.corp.com:125', 'Fully-qualified DNS name with port',
+  );
+
+  plan tests => (scalar(@lives_tests) + scalar(@dies_tests))/2;
+
+  while (my ($host, $test_name) = splice @lives_tests, 0, 2) {
+	lives_ok(sub {Email::Sender::Transport::SMTP->new({ host => $host })}, $test_name);
+  }
+
+  while (my ($host, $test_name) = splice @dies_tests, 0, 2) {
+	dies_ok(sub {Email::Sender::Transport::SMTP->new({ host => $host })}, $test_name);
+  }
+};