You will have to follow these steps :
1. Update spf record we added with IP address of printer,
For example, if your sending device sends from 18.104.22.168, then add that address to your SPF record without removing the Google Apps mail servers from the record: v=spf1 ip4:22.214.171.124 include:_spf.google.com ~all
2. Whitelist same IP address in your admin console, For that follow below steps :
- Sign in to the Google Admin console.
- From the dashboard, go to Google Apps > Gmail > Advanced settings.
- In the Organizations section, highlight your domain.
- In the Email whitelist section, enter the IP addresses of your contact's domain host to make sure any mail originating from these IP addresses are not labeled spam. If you would like to add more than one IP address, enter an IP range in CIDR notation or separate each IP address with a comma.
- Click Save changes.