We used Exim instead of Maildir.
Exim is a mail transfer agent used on Unix-like operating systems. It is freely available under the GNU GPL and it aims to be a general and flexible mailer with extensive facilities for checking incoming e-mail.
If you can not send email using mail.yourdomainname.com as your SMTP server, it may be...
Please check if port 2095 is open or not. Go to http://www.canyouseeme.org to check if you are...
If you aren't able to send this usually means one thing... your internet provider is blocking...
Either your domain is over quota, or your e-mail address itself is over quota. You will need to...