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By default, my mail server (Snow Leopard) contains an entry to only accept SMTP relays from However, when I attempt to check the option and save, the computer unchecks it. When I change the IP address to just, I don't experience the unchecking problem. There are two possible solutions: either do you know what is causing the unchecking problem (or which configuration file should I edit to manually do this?), or is it acceptable to simply only have as the IP address?

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up vote 0 down vote accepted

I don't have a 10.6 server handy to check with, but I'm pretty sure the default ("Accept SMTP..." option unchecked) setting is to allow relay from Essentially, there are two different ways to get the same setting, you're entering one, and it's displaying the other. You can verify this by looking in /etc/postfix/ for a line starting with "mynetworks =".

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I checked the option, changed mynetworks to, and it works. Thanks for your help! – Jack Humphries Jan 19 '13 at 17:32

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