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For a new business, I need to run my own SMTP server out of my home. I can't use the SMTP servers of either our web host or our ISP because of limitations they place on outgoing emails. For example, our web host limits as follows:

1000 emails per day

< 500 emails per 5 minute window

100 recipients per email

Now, I've got two iMac's running OS X Snow Leopard and I understand postfix is available. I've just converted our FIOS Internet to static IP. Does anyone know of a resource that will help me make one of my machines an SMTP server and allow me to use Mail.app as the client to send the messages through the server?

Note: I've seen the following messages but they still use postfix in conjunction with a relay SMTP. How do I avoid the web host / isp SMTP server in sending emails?

Terminal mail delivery delay in Mac OS X

How to use mail or sendmail on Snow Leopard


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migrated from superuser.com Aug 25 '12 at 4:40

This question came from our site for computer enthusiasts and power users.

It's been a couple years since this question was active. @Motivus, how did it work out for you? Did you get your own outbound SMTP server running? –  Doug Harris Jul 23 '13 at 16:18

4 Answers 4

I run my own mail servers from my home on a business connection. Don't be discouraged if that is what you really want to do, but heed the advice above and just know - it 'aint easy. You'll be constantly bombarded by people from China, Amsterdam, et al. Servers will have to stay up 24/7 to send and receive mail, you'll need to have proper DNS and PTR records setup up, along with many other things. And if you do get blacklisted for spam (which is extremely easy) your static IP will be useless for mail until it's fixed. With those kind of limits, as explained, mail chimp or constant contact is your best bet.

If you are certain that you want to do this, then it is my suggestion that you take your OS X Server and run some virtualization software with a few VMs to get things started. It's a great way to tinker with your sever's configuration and have the ability to snapshot and roll changes back. Plus, you can pick up a VM all ready setup with lots of handy tools from turnkey linux or from the VMWare app store.

I highly recommend the VMs from Turnkey Linux since they (often times) have Webmin, a web-based management GUI, built right in and the wizard walks you through setting up any passwords or required settings.

It probably took me 5 years to get comfortable enough with courier, postfix, and linux OS to get the confidence up to run my own mail servers without having tech support to fall back on or a huge data center (of course my datacenter isn't too shabby...). Maybe I'm overly cautions, but I live in my email box.

I also recommend OSSEC for intrusion detection.

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Thanks for your reply. I don't discourage easily... even though I'm slowly realizing what I'm up against. A few details: I don't need this in-house SMTP server to up 24/7... I just need it up for the length of time required to send emails (and thus fulfill orders). Can you elaborate on the need for a fixed IP? I thought having a static IP would be enough... –  Motivus Mar 22 '11 at 0:36
You can't legitimately send emails without a PTR and this needs to be set by your ISP. Receiving mail servers will do multiple checks before excepting your mail. One is a rDNS on your IP - "Does this IP's PTR record have a non-generic record?" (not an 123.123.123.comcast.net) If it does not, mail will be rejected. If your IP is in a 'home IP' or a 'dynamic IP block' mail will also be rejected. You can't just fire up a server and start sending mail. It's not like that anymore. Of course, if your ISP has an open relay you could send it through there. –  skub Mar 22 '11 at 1:13
Skub, thanks again. Just dawned on me that we might be talking past one another. I'm saying static IP and you're saying fixed IP... but aren't they one in the same? (As in not dynamic.) Today I upgraded our Verizon FIOS from residential (and dynamic) to business (and static). –  Motivus Mar 22 '11 at 2:16
As Skub said, there is a lot more to running an email server than just installing a package and turning it on. –  micmcg Mar 22 '11 at 7:18
This is why I'm looking for a good resource that will help me get postfix set up and properly configured. This may be hard... this may be non-intuitive... but I'm an engineer and this is what I do. I've got two machines that can do the job. I've got a fixed (aka static) IP coming. I just need a solid resource or two that can step me through the OS X Snow Leopard (not server) install / setup / test process. Also, @skub, does it make a difference if I will only use the machine to send email? I won't need to leave it on 24/7... –  Motivus Mar 22 '11 at 11:46

You've linked to two questions I've answered on, but here's an answer to a question about desktop mailing list management that is probably appropriate for your question as well.

The key thing to realize is that the limits your ISP puts in place are there to prevent the ISP from being labeled as a spammer -- either by its users intentionally sending spam or by its users being infected with software that makes them unwitting clients in a spam botnet.

If your business has a legitimate reason for sending mass quantities of email, you're probably better off letting a professional service handle the headaches of making sure your email gets delivered.

If you still want/need to do it yourself, you'll probably want a server in a co-location facility -- not something inside a residential or small business ISP's network.

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Thanks Doug. Unfortunately, we can't use Constant Contact or other email marketing services because we need to send out a unique PDF attachment with each email... and the process needs to be automated to boot. I don't believe CC allows email attachments... and then the process of uploading them and associating them with a customer will be a nightmare. We are definitely a legit business... but no matter how I look at the problem I keep coming back to hosting our own mail server. Why would I need a collocation facility if I've got a static IP address and a box that's able to send email? –  Motivus Mar 21 '11 at 22:50
It will all come down to the terms of your agreement with your ISP. Trying to get around it could cut you off. –  Doug Harris Mar 21 '11 at 23:51
I am trying to get around the limitations on email sent through our web host's SMTP server, not our ISP. I've never used our ISP's mail servers. But I'm not perfectly sure I understand your point. If I configure our own in-house SMTP server and send mail directly (using no relay) won't my email traffic just be plain old traffic to my ISP? Why will they care what I'm sending? I could be uploading new pics to Facebook for all they know. (Or is that just plain naive??) –  Motivus Mar 22 '11 at 0:46
Standard email configuration for a desktop client would connect to your ISP's mail server. Your SMTP server will want to connect to port 25 on an external server or directly on the email recipients' mail servers. Your ISP can block traffic from within its network to port 25 on any server other than the few it designates. The ISP cares because it doesn't want its customers sending spam. skub's answer goes into more details about the stuff you'll need to set up. –  Doug Harris Mar 22 '11 at 14:25

As Doug Harris said, the limits are there to stop the ISP being flagged as a spammer, and if you try and circumvent them, you are likely to be flagged as a spammer. Email delivery is hard, you should let someone else do the heavy lifting to ensure delivery. Have you looked at http://sendgrid.com/ and http://aws.amazon.com/ses/ ? These are not the same as Constant Contact, Campaign monitor, mail chimp etc

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In my case I would be sending email to customers who've made purchases through our website. So the customers would be expecting our email and unlikely to flag it as spam. But, as I said in response to Doug, I need to send a individualized PDF attachment along with the email message.... and I think it's unlikely this process can be streamlined if I need to send out 500 or 1000 or more a day. That's why I'm looking at rolling my own in-house solution. If the people we're emailing are expecting our emails - and they're going out individually - will our emails be stopped by other mail servers? –  Motivus Mar 21 '11 at 23:06
If you think that the end user flagging a message as spam is the only way you will get blacklisted, then you really don't understand the issues with mail delivery and I STRONGLY recommend that you let a 3rd party handle the hassle. Did you look into the sites I recommended? I don't think there is any reason why you couldn't do what you want with Sendgrid or SES. Do you really want to spend your time managing an email server, or do you want to spend it improving your product? How long before the cost of your time exceeds the costs of a 3rd party service? –  micmcg Mar 22 '11 at 7:09
Also am I reading correctly, do you run the webserver out of your home as well? –  micmcg Mar 22 '11 at 7:10
No, we have a web host - they currently host our website and our email. I did look into Sendgrid and SES last night... with the intent of calling and talking to someone today. Again, the critical point for me is what I need to do to fulfill orders. I can't imagine a scenario where I've got to upload 500 or more PDFs a day and link them - either as an attachment or with a custom url - to 500 or more individual outgoing emails. If Sendgrid or SES will allow me to have an account and send the emails out myself via their SMTP servers - without a 1000/day limit - then GREAT. –  Motivus Mar 22 '11 at 11:38
Thats exactly what they do. You'll just need to need to confirm that they allow attachments (I can't see why they wouldn't), but you can definitely treat sendgrid like a normal SMTP server - sendgrid.com/documentation/settingsSMTPPHPEmail –  micmcg Mar 22 '11 at 23:05

Just spend the money to buy a copy of Leopard Server. You'll find it doesn't cost that much to buy a NOS copy on eBay, and having the legitimate serial number and other server tools makes it worth it. Snow Leopard server will probably be supported long enough to insure your business model works, and the server version makes SMTP configuration almost trivial (though even on mine I use some filters on eMails and have my settings so I can't be used as a relay host).

From there you can write a short program to edit submission to name the attachment using the X-Attachment field on a per customer eMail basis from a simple flat database either using SQL (overkill) or writing something small and custom that keeps records in XML format so you can easily transition systems later if you need something more powerful.

I've been using Leopard Server on an old dual core G5 machine for some time now as my primary mail server, and haven't had a bit of problem with it. Not only is it working at my SMTP server and POP/IMAP server but it triples as a DNS server and WWW server as well as hosting other services. Runs without problem handling MUCH data off my Verizon commercial FIOS line.

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