Five Golden Rules for Outbound Email
1. Always send using a FROM domain you control.
Do not send email messages on behalf of customers, and never use customer email addresses in the FROM field. Also, avoid sending from addresses associated with DNS records you don’t control.
For emailed forms or messages related to transactions, ensure that the 'Return Email Address' field on the Company Information page specifies your domain. (Administrators can navigate to Setup > Company > Company Information to view and edit this field).
2. Manage Your Scripts.
Regularly review your SuiteScript outbound email scripts if you use automated custom email notifications. Promptly delete any obsolete scripts or customizations that are no longer in use.
3. Be Compliant.
Ensure you have proper DNS records set up for DKIM on the domains you send emails from. Consider implementing a DMARC policy record for your company’s entire email infrastructure. While it’s not necessary to set up DNS records for SPF on the domains you send emails from for NetSuite purposes, depending on your company's requirements, creating an SPF DNS record may be necessary.
4. Be Aligned.
If you use an email relay between NetSuite and your mailbox provider (where the MX points), ensure that the MAIL-FROM (ENVELOPE-FROM, RETURN-PATH) passes the SPF check.
5. Be Hygienic.
Never send spam or unwanted emails. Avoid sending the same email multiple times. Always respect unsubscribe requests. Do not send or forward emails with unknown content, especially attachments.
You may refer to the related articles regarding emails below
Not Sent: Blocked by Mail Filter Reason for Undelivered Emails to Recipients
Remove Adobe Hyperlink on Invoice Email Template Footer