• Mail Server

Configuring a mail server is out of scope for this documentation.

++ Supported SMTP Servers

• Any mainstream SMTP server will work (postfix, exim - most likely even sendmail will do)
• Testing was mostly done against postfix 3.4 - 3.7
• Horde supports TLS and STARTTLS as well as plain connections (unsecure, use only in local networks)

++ Supported Mail Filters

• You only need a mail filter if you use IMP webmail and the ingo filter application
• Testing was mostly done against dovecot sieve
• Cyrus Sieve and Timsieved are known to work but ancient versions cause trouble
• No testing was done for procmail. There is no obvious reason why it should not work

++ Supported IMAP Servers

• You need no imap server for most horde apps besides IMP webmail
• Any mainstream imap server will work (dovecot, cyrus, courier)
• testing was mostly done against dovecot 2.3
• Horde supports TLS and STARTTLS as well as plain connections (unsecure, use only in local networks)