====== Issues ======

====== F=<>: Unrouteable address ======

<code>
www-data@hostnaname.example.com F=<>: Unrouteable address
</code>

Test routing path:
<code>
exim -bt www-data@example.com

DEBUG: system_aliases for www@example.com
DEBUG: procmail for www-data@example.com
www-data@example.com is undeliverable: Unrouteable address
</code>

So the reason of problem is suffix based aliases search pattern. Address ''www-data'' is translated to ''www'' which doesn't exists.

**Workaround:**  add some workaround aliases like:
<code>
www@example.com: user
www: user:
</code>


====== unable to set gid=33 ======

<file /var/log/exim4/paniclog>
...
2019-07-13 09:14:44 unable to set gid=33 or uid=0 (euid=0): forcing real = effective
2019-07-13 15:38:11 unable to set gid=33 or uid=0 (euid=0): forcing real = effective
...
</file>

Reproduction:
<file php mailtest.php>
<?php
    $email = "user@domain.com";
    $subject = "test z phpa";
    $message = "lorem ipsum";

    $mail = \mail($email, $subject, $message);
    print ($mail);
?>
</file>

Reason:

**Apache Module MPM ITK**
The MPM ITK Apache module implements restrictions on the use of the setuid() function and the setgid() function. As a result, scripts that depend on these functions may encounter problems. This includes scripts that use the mail() function, the shell_exec function, or the sudo command. 

You can resolve these restrictions with one of the following methods:

  * Do not use the MPM ITK Apache module. 
  * Update your script to no longer require escalated privileges.
  * Turn off the security and allow users to execute scripts as the root user. You can allow users with a UID or GID between 0 and 4294496296  to bypass security if you add the following code to your ''/etc/apache2/conf.d/includes/pre_virtualhost_global.conf'' file. 
    <file>
    <IfModule mpm_itk.c>
    LimitUIDRange 0 4294496296
    LimitGIDRange 0 4294496296
    </IfModule>
    </file>
    
    **Warning:**  We strongly recommend that you do not enable root privileges for your users. This action has major security implications and could endanger your server.

To work around it, you would have to change your php or php-apps to 
send mails via SMTP to localhost instead of invoking /usr/lib/sendmail 
directly. I can't give any advice on how to do that, though. Or maybe 
there is some way to install some minimal MTA like ssmtp or nullmailer 
as /usr/lib/sendmail that forwards the mail to exim via SMPT. Not sure 
how easy it is to install those parallel to exim, though. Maybe it 
could work by diverting exim's /usr/lib/sendmail .