diff -pruN 2.6.4-1/debian/changelog 2.6.4-1ubuntu1/debian/changelog
--- 2.6.4-1/debian/changelog	2017-06-30 19:45:09.000000000 +0000
+++ 2.6.4-1ubuntu1/debian/changelog	2018-02-20 22:41:08.000000000 +0000
@@ -1,3 +1,10 @@
+php-horde-mail (2.6.4-1ubuntu1) bionic; urgency=medium
+
+  * debian/patches/phpunit6_compat.patch: PHPUnit 6 has namespaced
+    classes.
+
+ -- Nishanth Aravamudan <nish.aravamudan@canonical.com>  Tue, 20 Feb 2018 14:41:08 -0800
+
 php-horde-mail (2.6.4-1) unstable; urgency=medium
 
   * New upstream version 2.6.4
diff -pruN 2.6.4-1/debian/control 2.6.4-1ubuntu1/debian/control
--- 2.6.4-1/debian/control	2017-06-30 19:45:09.000000000 +0000
+++ 2.6.4-1ubuntu1/debian/control	2018-02-20 22:41:08.000000000 +0000
@@ -1,7 +1,8 @@
 Source: php-horde-mail
 Section: php
 Priority: extra
-Maintainer: Horde Maintainers <pkg-horde-hackers@lists.alioth.debian.org>
+Maintainer: Ubuntu Developers <ubuntu-devel-discuss@lists.ubuntu.com>
+XSBC-Original-Maintainer: Horde Maintainers <pkg-horde-hackers@lists.alioth.debian.org>
 Uploaders: Mathieu Parent <sathieu@debian.org>
 Build-Depends: debhelper (>= 9), pkg-php-tools (>= 1), pear-horde-channel
 Standards-Version: 3.9.8
diff -pruN 2.6.4-1/debian/patches/phpunit6_compat.patch 2.6.4-1ubuntu1/debian/patches/phpunit6_compat.patch
--- 2.6.4-1/debian/patches/phpunit6_compat.patch	1970-01-01 00:00:00.000000000 +0000
+++ 2.6.4-1ubuntu1/debian/patches/phpunit6_compat.patch	2018-02-20 22:41:06.000000000 +0000
@@ -0,0 +1,104 @@
+Description: PHPUnit 6 has namespaced classes
+Author: Nishanth Aravamudan <nish.aravamudan@canonical.com>
+Forwarded: Will be done by Nishanth Aravamudan
+Last-Update: 2018-02-20
+
+--- php-horde-mail-2.6.4.orig/Horde_Mail-2.6.4/test/Horde/Mail/AddressTest.php
++++ php-horde-mail-2.6.4/Horde_Mail-2.6.4/test/Horde/Mail/AddressTest.php
+@@ -7,7 +7,7 @@
+  * @subpackage UnitTests
+  */
+ 
+-class Horde_Mail_AddressTest extends PHPUnit_Framework_TestCase
++class Horde_Mail_AddressTest extends PHPUnit\Framework\TestCase
+ {
+     /**
+      * @dataProvider domainMatchProvider
+--- php-horde-mail-2.6.4.orig/Horde_Mail-2.6.4/test/Horde/Mail/GroupTest.php
++++ php-horde-mail-2.6.4/Horde_Mail-2.6.4/test/Horde/Mail/GroupTest.php
+@@ -7,7 +7,7 @@
+  * @subpackage UnitTests
+  */
+ 
+-class Horde_Mail_GroupTest extends PHPUnit_Framework_TestCase
++class Horde_Mail_GroupTest extends PHPUnit\Framework\TestCase
+ {
+     /**
+      * @dataProvider writeAddressProvider
+--- php-horde-mail-2.6.4.orig/Horde_Mail-2.6.4/test/Horde/Mail/IdentificationTest.php
++++ php-horde-mail-2.6.4/Horde_Mail-2.6.4/test/Horde/Mail/IdentificationTest.php
+@@ -23,7 +23,7 @@
+  * @package    Mail
+  * @subpackage UnitTests
+  */
+-class Horde_Mail_IdentificationTest extends PHPUnit_Framework_TestCase
++class Horde_Mail_IdentificationTest extends PHPUnit\Framework\TestCase
+ {
+     /**
+      * @dataProvider provider
+--- php-horde-mail-2.6.4.orig/Horde_Mail-2.6.4/test/Horde/Mail/ListTest.php
++++ php-horde-mail-2.6.4/Horde_Mail-2.6.4/test/Horde/Mail/ListTest.php
+@@ -7,7 +7,7 @@
+  * @subpackage UnitTests
+  */
+ 
+-class Horde_Mail_ListTest extends PHPUnit_Framework_TestCase
++class Horde_Mail_ListTest extends PHPUnit\Framework\TestCase
+ {
+     private $rfc822;
+ 
+--- php-horde-mail-2.6.4.orig/Horde_Mail-2.6.4/test/Horde/Mail/MatchTest.php
++++ php-horde-mail-2.6.4/Horde_Mail-2.6.4/test/Horde/Mail/MatchTest.php
+@@ -7,7 +7,7 @@
+  * @subpackage UnitTests
+  */
+ 
+-class Horde_Mail_MatchTest extends PHPUnit_Framework_TestCase
++class Horde_Mail_MatchTest extends PHPUnit\Framework\TestCase
+ {
+     /**
+      * @dataProvider matchProvider
+--- php-horde-mail-2.6.4.orig/Horde_Mail-2.6.4/test/Horde/Mail/MboxParseTest.php
++++ php-horde-mail-2.6.4/Horde_Mail-2.6.4/test/Horde/Mail/MboxParseTest.php
+@@ -23,7 +23,7 @@
+  * @package    Mail
+  * @subpackage UnitTests
+  */
+-class Horde_Mail_MboxParseTest extends PHPUnit_Framework_TestCase
++class Horde_Mail_MboxParseTest extends PHPUnit\Framework\TestCase
+ {
+     public function testMboxParse()
+     {
+--- php-horde-mail-2.6.4.orig/Horde_Mail-2.6.4/test/Horde/Mail/ObjectTest.php
++++ php-horde-mail-2.6.4/Horde_Mail-2.6.4/test/Horde/Mail/ObjectTest.php
+@@ -7,7 +7,7 @@
+  * @subpackage UnitTests
+  */
+ 
+-class Horde_Mail_ObjectTest extends PHPUnit_Framework_TestCase
++class Horde_Mail_ObjectTest extends PHPUnit\Framework\TestCase
+ {
+     public function testWriteAddress()
+     {
+--- php-horde-mail-2.6.4.orig/Horde_Mail-2.6.4/test/Horde/Mail/ParseTest.php
++++ php-horde-mail-2.6.4/Horde_Mail-2.6.4/test/Horde/Mail/ParseTest.php
+@@ -7,7 +7,7 @@
+  * @subpackage UnitTests
+  */
+ 
+-class Horde_Mail_ParseTest extends PHPUnit_Framework_TestCase
++class Horde_Mail_ParseTest extends PHPUnit\Framework\TestCase
+ {
+     private $rfc822;
+ 
+--- php-horde-mail-2.6.4.orig/Horde_Mail-2.6.4/test/Horde/Mail/SendTest.php
++++ php-horde-mail-2.6.4/Horde_Mail-2.6.4/test/Horde/Mail/SendTest.php
+@@ -7,7 +7,7 @@
+  * @subpackage UnitTests
+  */
+ 
+-class Horde_Mail_SendTest extends PHPUnit_Framework_TestCase
++class Horde_Mail_SendTest extends PHPUnit\Framework\TestCase
+ {
+     /* Test case for mixed EOLs. */
+     public function testMixedEOLs()
diff -pruN 2.6.4-1/debian/patches/series 2.6.4-1ubuntu1/debian/patches/series
--- 2.6.4-1/debian/patches/series	1970-01-01 00:00:00.000000000 +0000
+++ 2.6.4-1ubuntu1/debian/patches/series	2018-02-20 22:40:42.000000000 +0000
@@ -0,0 +1 @@
+phpunit6_compat.patch