Setting up hybrid mail (Google Workspace + Secondary server + SendPulse)

General concept: Google Workspace acts as a "gateway". Emails first arrive at Google. If such a mailbox does not exist in Google, it forwards the email to a secondary server (Hetzner or similar). Important note: The server must have routing configuration functionality and support External/Remote Mail Delivery mode.

1. DNS configuration (on the GoDaddy side)

It is necessary to ensure the authorization of all three sending sources:

MX records: Specify only Google servers (ASPMX.L.GOOGLE.COM, etc.). Attention: Do not add MX records for Hetzner/another server.

SPF record (TXT): Must include all nodes:

v=spf1 ip4:168.119.26.114 include:_spf.google.com include:mxsspf.sendpulse.com ~all.

(Instead of IP 168.119.26.114, specify the current IP address of the chosen mail server).

DKIM & DMARC: Generate TXT records for Google and SendPulse to prevent landing in spam.

2. Google Workspace configuration (Primary server)

Setting up Split Delivery logic:

Adding Host: In Apps > Google Workspace > Gmail > Hosts, add the secondary server (for example, www634.your-server.de or the IP address of another provider).

Routing (Default Routing):

Create a rule for "Unrecognized recipients".

Select the action "Change route" and specify the previously created Host.

This activates the forwarding of emails that are not in Workspace to the secondary server.

3. Configuration of the secondary server (Hetzner or another)

Hetzner (konsoleH): It is necessary to activate "Mailsystem", but send a request to support to switch the domain to "External" mode (so that the server does not look for mail locally when sending to Google).

Other servers (SiteGround / A2 Hosting): In the control panel (cPanel or Site Tools), set Email Routing to "Remote Mail Exchanger" by yourself.

Mailboxes: Create only those service addresses on this server that are not present in Google Workspace.

4. SendPulse

Used exclusively for marketing mailings.

Check domain validation through the DNS records specified in item 1.