Mac Server - Postfix Issue on certain ISP
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I have Mac Server and MAMP running as my local server, and have set up Postfix in MAMP to enable outgoing mail.

I have the smart host set as gmail.com

When I connect the machine to the internet using my mobile phone network (vodafone), all works perfectly.

However, when I connect the machine to the internet with my normal ISP, through my LAN, postfix returns the error:

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Host or Domain name not found. Name service error for name=gmail.com type=MX Host not found, try again
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I have tried it changing the smarthost to the ISP's mail.isp.com, same issue.

Using the command dig gmail.com (or indeed dig myisp.com) it ONLY returns A names, no MX. A 'dig gmail.com MX' (or dig myisp.com MX) returns a timeout.

My LAN is a router behind a modem, nothing more than that.

So, where should I start?

The fact it works on my vodafone ISP suggests it's either an issue with my normal ISP blocking something? or my local network set up?

Any suggestions, most appreciated.

Thanks
