In order for email avoid security alerts or refusal of emails sent through SFDC on behalf of any user, company needs to configure proper SPF DNS records.
This configuration is optional and not directly related to ClosePlan or People.ai, the customer is responsible and it should be actually in place already, because its highly likely that customer’s SFDC org is sending out .
It is really common that Salesforce sends emails on behalf of users. Unfortunately, not every company knows that such configuration should be provided…, such as email alert workflows or custom Apex initiated notifications and it also applies to any email notification sent by ClosePlan application.
In order to avoid security alerts or even refusal of such emails, proper SPF record should be configured in your DNS settings.
To setup SPF records, please follow steps in the official Salesforce article:
https://help.salesforce.com/articleView?id=000315520
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