If you want to send from [email protected], while having mail.companyname.com as your SAP domain, there are few things to observe. This is doable, but you must also purchase Private Domain SKU (in addition to SAP SKU)
- SAP domain is mail.companyname.com. This makes bounce domain bounce.mail.companyname.com
(needs to be in same domain as corporate domain for DMARC compliance)
Click domain will be click.mail.companyname.com, etc.
- Private Domain should be company.com
This Private Domain DNS will be custom and client hosted. You need to reach out to support to get the right DNS settings, and implement only the DKIM-related DNS entries.
Don’t implement Salesforce MX record for the private domain or it will break your corporate mail! You can now disable RMM, so that replies go directly back to corporate employees. Provide dedicated IP info to support, so this private domain will send from the SAP IP address.
Also, since your SAP domain is under a different domain than your private domain, the DMARC will fail, as both should be under the same domain (i.e. your SAP domain should be mail.company.com). In order to overcome this, you should ask support to enable “multi-bounce domain” feature, when adding your new private domain, to ensure your private domain will comply with DMARC.
Also, username (part before @) does not have any impact on deliverability, as long it comes with an authenticated email domain (SAP or Private Domain)