Go to Lists > Relationships > Bounced Email Addresses to determine if the recipient’s email address is on the bounced list. If the email address is in the list, delete the email from the list by marking the Delete checkbox for each email address in the list. You can also use the Mark All button and then click the Delete button to clear the email addresses in the Bounced Email Address list, you can then try and resend the email.

Determine whether the email was blocked by NetSuite or if it was rejected on the destination mail system by going to Setup > Company > Communication > Sent Email List. This provides a view of all outgoing emails sent from your account. The list gives you the following details of all outgoing emails:
a. Send Date, Log Date, Sender (From)
b. Subject
c. Recipients (To,Cc,Bcc)
d. Body
e. Message ID
f. Status (if Sent or Not Sent)
g. Compliance Verified

To get more information on the delivery status, click the corresponding row number of the email.

tips 1

If the Compliance Verified column is set to No, go to Setup > Company > Email > Email Preferences. On the Domain Keys subtab, setup a DKIM key for the domain populated by the customer in the From header of the sent email.

Verify your DKIM Setup by going to Setup > Company > Email > Email Preferences and click on the Domain Keys subtab.
a. Click the Verify DNS Entry button.
b. If you receive a message that your DNS entry for DKIM has been verified, click Send Test Email to DKIM Reflector to send a test message. A report is sent to the Email Address to Receive Test Response field.

tips 2