Smart host external SMTP relay

[MrMatt]

Hi All

We are planning to host WHM in Google and so require SMTP relay.
I've read some brilliant and not so brilliant articles on here, that have helped me.

Google requires instances to send mail via relay.
Sending Email from an Instance  |  Compute Engine Documentation  |  Google Cloud Platform

So far I have looked at :

Smart host.
Exim Configuration Manager - Basic Editor - Documentation - cPanel Documentation

We trialled exim with this config.
Exim 4 configuration for SendGrid - SendGrid Documentation | SendGrid

This would send emails but could not receive.

Wonder what other options there are out there ? I found this forum post.
Smart Host - Exim Cpanel - SMTP external outgoing mail server

I'd like some more clarity on the high level overview, would a simple postfix server with IP auth be acceptable to send mail on behalf of approx 200 domains ?

Also wondering if setting the MX records to the GCP instance is ok once the smart host config is done ?

Lastly does this set up have any issue with SSL certs and or mail headers and spf / dkim / anti spam when sending to sensitive recipients in Outlook etc etc.

Many thanks if you can join in with this discussion.

Kind Regards

Matt

 

[cPanelMichael]

We trialled exim with this config.
Exim 4 configuration for SendGrid - SendGrid Documentation | SendGrid

This would send emails but could not receive.

Hello,

Those instructions should work. Could you provide information about the logs you noticed in /var/log/exim_mainlog when you could not receive emails? Did you perform any additional troubleshooting steps?

Thank you.

 

[MrMatt]

Hi Michael


From memory I think it was to do with the inbound parsing in the Sendgrid admin settings. You basically get one domain or path to parse all inbound email which we could not see how this would work with all the domains hosted under one WHM server,

This is the documentation link
Setting Up The Inbound Parse Webhook - SendGrid Documentation | SendGrid

This is why I was wondering would it be better to use Smart host and setup an SMTP relay server?

Perhaps there can be a combination of the two do you know Smart Host for customer emails + Exim Conf for emails sent by Sendmail in php and php alerts ?

Kind Regards

Matt

Hello,

Those instructions should work. Could you provide information about the logs you noticed in /var/log/exim_mainlog when you could not receive emails? Did you perform any additional troubleshooting steps?

Thank you.

 

[MrMatt]

Michael

Just looking at Mail gun inbound mail docs, it appears you can setup rules for inbound so some can forward through the SMTP server if the MX records point to domain to the Smart host mail server ?

I was thinking of experimenting with a postfix server we have to see if this could work. My concern was mail authentication with the SMTP smart host whether it requires one master user / password or would the SMTP servers need to have the cpanel accounts as per the WHM server ?

 

[MrMatt]

Michael

Here is the doc for Mailgun inbound

How to start receiving inbound email — Mailgun API documentation

 

[cPanelMichael]

Hello,

You may find this URL (and the comments on it) helpful regarding MailGun and cPanel:

3sq.re - Configure Exim on cPanel to use Mailgun

Note that you are welcome to test out the inbound email configuration, but Google only requires the smart host configuration for outgoing emails.

Thank you.