We send out a pretty volume of emails right now using a combination of SQL and IIS SMTP. We get rates now of about 5,000/min. We're looking to not only improve the rates, but incorporate DKIM/Domainkey signing into the process. The choice has been made to go with postfix along with a queue directory on an XFS file system.
I'm using postfix as a relay, and having it sign the outgoing emails with DKIM. That process was about twice as slow as without it. Without DKIM, I'm getting a rate of 700/min. I was expecting much better performance out of the box. I realize in my tests I'm going from a single host, to another single postfix box that is receiving all the emails to one account, so there may be bottlenecks that exist in my test setup, that may not be there in our production environment. I'm really hoping to move away from MS SMTP and don't have tons of experience with Linux, so I'm hoping people could give me some good ideas about improving outbound performance. The server will not be directly exposed to the internet, so security is less of a concern as it will be behind several Cisco firewalls. This server will not be receiving any email, so nothing needs to be considered for that side. Thanks, Brandon
