It does. Thanks for the quick fix!

This should fix things (?)

Changes have been made in Git for this ticket:

Bug #9525: Switch header charsets if we can't encode properly

http://git.horde.org/horde-git/-/commit/0c59c79c42530ea086a137b065da74d6292704f7

In both tests you use 'UTF-8' as charset. In my case 
$message->getHeaderCharset() returns 'us-ascii' which is probably 
causing the problems. I'm replying to another message. Might that 
result in assuming an incorrect character set here?

Yes.  The email address should be MIME encoded after that call, so it 
will pass validation (since it no longer contains non-7bit characters).

Added some tests to horde/Mime - both pass for me.

Changes have been made in Git for this ticket:

Bug #9525: Add Horde_Mime::encodeAddress() tests

http://git.horde.org/horde-git/-/commit/8696a5446ebb64c22233e6ec37f6379ae42eb98c

Ah, I see. Thanks for the feedback.

The validation fails on l.850 in imp/lib/Compose.php. Is the 
Horde_Mime::encodeAddress call above it the one that should quote it?

Except this *is* an invalid address.  The ß must be quoted - if it is, 
the validation correctly passes.

So for whatever reason this character is being quoted when I send a 
message but not when you send a message.  We need to find where in IMP 
this quoting is failing to occur (unit tests are unfortunately not 
going to help us here :( ).

Changes have been made in Git for this ticket:

Bug #9525: Add validation tests

http://git.horde.org/horde-git/-/commit/d17e468f3b8c781100fad3bfadb305fdd4164b5d

The following test for the "Mail" package reproduces the problem on my side:

diff --git a/framework/Mail/test/Horde/Mail/ParseTest.php 
b/framework/Mail/test/Horde/Mail/ParseTest.php
index f095c1c..fec8988 100644
--- a/framework/Mail/test/Horde/Mail/ParseTest.php
+++ b/framework/Mail/test/Horde/Mail/ParseTest.php
@@ -189,4 +189,16 @@ class Horde_Mail_ParseTest extends 
PHPUnit_Framework_TestCase
          $this->assertEquals(count($res), 3);
      }

+    public function testBug9525()
+    {
+        $parser = new Horde_Mail_Rfc822();
+        $ob = $parser->parseAddressList(
+            'ß <wrobel@pardus.de>',
+            array(
+                'default_domain' => 'pardus.de',
+                'nest_groups' => false,
+                'validate' => true
+            )
+        );
+    }
  }


Having a unit test now I assume I would be able to solve it myself. I 
just wont find the time today anymore and in case you immediately spot 
the problem I'm of course happy if I don't have to dive into the code :)

I don't see this.  Just sent a message and it worked fine.  Headers:

[...]
To: =?utf-8?b?w58=?= <slusarz@curecanti.org>
Subject: Test
User-Agent: Internet Messaging Program (IMP) H4 (5.0-git)
[...]

Not quite certain if the problem is caused by non-ascii letters in 
general but when trying to send a message to

ß <wrobel@horde.org>

in the dynamic version of imp I get the error that sending of the 
message failed with

Validation failed for: ß <wrobel@horde.org>