1. Install.
2. Set up a local.conf with local settings that override:
3. set the certificate locations:
   ssl=required ssl_cert = </etc/ssl/mail/helical.com.pem ssl_key = </etc/ssl/mail/helical.com.pem
4. set the password information for virtual users:

Tough one to crack.

1. install solr
2. rebuild dovecot with solr enabled
3. create a file called /var/db/solr/dovecot/conf/elevate.xml
4. copy /var/db/solr/solr/conf/elevate.xml to /var/db/solr/dovecot/conf/elevate.xml
5. change the owner of the above file to "solr"

Highly non-obvious, but revealed by tracking /var/log/maillog and /var/log/solr/solr.log

Now, to access: ssh -L 8983:localhost:8983

Essentially, setting postfix to generate a trackback header to each message will reveal how a message was generated.

...until you add a SMART optional argument "-d sat".

First, read this.

Lmtp is the preferred local mail transport protocol: runs a constant single process in the background, so faster and less resource strain on the system.

You need to change the local mail transport setting for postfix to:

First, read this. Then, read this.

Except, in dovecot/local.conf:

smtpd_use_tls = yes lda_mailbox_autocreate = yes lda_mailbox_autosubscribe = yes protocol lda { # Space separated list of plugins to load (default is global mail_plugins). mail_plugins = sieve $mail_plugins protocols = $protocols sieve

Configure 

Getting SASL authentication to work inbound requires that the sending SMTP server have proper SASL settings -- which OS X doesn't make visible from the Server app. You have to set them on the CLI, thusly:

Read the "Integrating SpamAssassin into Postfix using spamd" from apache.org.

First, read this.

Regardless of what Namecheap says, its reverse DNS is broken and some mail servers won't recognize it. Digital Ocean assigns a reverse DNS entry to match the name of the droplet, so that works.