Connectivity and managing Your Comcast Business network
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Frequent Contributor

Using Comcast Business SMTP as an outbound Smarthost

I am a Comcast Business customer with one static IP address. My LAN is controlled by a Cisco RV325 VPN/VLAN appliance. What I want to do is implement a cron job on a Raspberry Pi that monitors a critical server elsewhere on my LAN and sends emails to maintainers in the outside world in the event of trouble. I have created and maintained Linux mail services on a small scale elsewhere (some postfix, some exim4)  so I know the basics. I have never done it here on Comcast Business.


So, this is very straightforward. I just want, on RARE occasions, to send a VERY FEW emails outbound only to be handled by Comcast Business SMTP using my existing account and password. I believe this technique is called SMTP Smarthost relay. I would like to know whether Comcast Business permits it, and if so, what do I need for configuration parameters for exim4 mail transfer agent on my Raspberry Pi.


I am aware there are posts in the Connectivity forum on this topic, but the ones I see are looking for remedies for something that wasn't working right.  I am just looking for a straightforward yes/no, and if yes, then the exim4 configuration settings would be great.


Thank you.

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Forum Contributor

Re: Using Comcast Business SMTP as an outbound Smarthost

If you have an email on the Comcast mailserver then yes, however the FROM address MUST match the Comcast email address assigned.


You can send mails from  you can't send them from 


You must also use auth-smtp

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New Member

Re: Using Comcast Business SMTP as an outbound Smarthost

I am not having success with sending from an on-premise device, even using the Primary Account holders Comcast business login as the sender and the authenicator using port 587 and auth-smtp.  Any ideas?


Thank you,

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