Postfix working as backend/local MTA

Question

I'm in the process of configuring an email platform and I would like to clear some doubts that I have.

When building this system I have 2 options:

1. Have PHP doing the connections to my SMTP external server (it's a delivery only server). This is how my network is configured at the moment and I feel it's very heavy on the server.
2. Have PHP connecting to my local MTA and having the local MTA (postfix) connecting through SMTP to my external delivery server

I think the option 2 is the preferable one for a couple of reasons:

• Dispatch from the email platform is faster
• PHP processes will finish faster
• Delivery itself will be on postfix (local MTA) responsibility thus creating a new layer on the delivery dataflow providing a lot more abstraction on the PHP platform
• Delivery rules can be defined specifically on Postfix

So, question 1 is if this is the preferable solution or if I should keep option 1?

Bellow is a small representation of what I'm referring in point 2:

                                                                  +------------+
                                                                  |            |
                              +---> smtp external backend a ----->|            |
                              |                                   |            |
platform -------> local MTA lb ---> smtp external backend b ----->|  Delivery  |
                              |                                   |            |
                              +---> smtp external backend c ----->|            |
                                                                  |            |
                                                                  +------------+

Question 2:

If this is the preferable situation how can I create a load balance postfix solution?

I need to be able to easily add and remove smtp servers.

Thank you!

Answer 1

First. Two questions in one is bad!

1) As you didn't find negative arguments for option 2 you should choose option 2.

2) You need no Postfix load balancer. Postfix on a recent machine is able to deliver 100 mails per second. With good hard-drives and a bit of queue management even more. I don't know why to extend that? And if you really really really need it then you should have an in-house DNS server with low TTL and use multiple A records for your local MTA (1b). The DNS is then doing round-robin load balancing for you.