Block Emails Sent from Unverified Email Addresses in the Guest User Record

To improve security standards, Salesforce is blocking any emails sent from an unverified email address in the guest user record starting with the Summer ’23 major release.

If you have custom implementations with Apex or flows that use emails sent from guest user records, you may need to make some changes to the guest user record to continue sending emails. 

You can continue sending emails from the guest user record using an organization-wide email address. Create an organization-wide email address if your org doesn’t already have one. Follow the steps to verify the organization-wide email address. Add the organization-wide email address in the Email field of the guest user record.

If you are using Apex to send emails from guest users, set the sender to the verified org-wide email address.
 

Sample code:
 

OrgWideEmailAddress[] owea = [select Id from OrgWideEmailAddress where Address =
'doNotReply@<somedomain>.com'];
Messaging.SingleEmailMessage mail = new Messaging.SingleEmailMessage();
if ( owea.size() > 0 ) {
mail.setOrgWideEmailAddressId(owea.get(0).Id);
}

Contact Salesforce Customer Support if you’re still having trouble sending emails from the guest user record.