Emails are not related to the intended Salesforce records when using the Salesforce for Outlook plugin, Outlook Integration (for logging emails on send), or Email to Salesforce. No bounce-back email is sent when this occurs.
When emails are sent to a Salesforce record using the Email to Salesforce feature (by BCC-ing the Email-to-Salesforce address), the emails are NOT associated and do not appear under the Activity History section of that record or in the Unresolved Items queue.
The most common cause is that Advanced Email Security Settings is enabled in the organization, and the user's email server does not support any of the following email authentication protocols: SPF (Sender Policy Framework), Sender ID (Microsoft's email authentication standard), or DomainKeys Identified Mail (DKIM).
When Advanced Email Security Settings is enabled, Salesforce uses these protocols to verify the legitimacy of the email sender's server. If the server does not pass at least one protocol, Salesforce does not process the email and it is not added to the record.
This article explains why emails sent via Email to Salesforce or Outlook Integration are not added to Salesforce records and provides steps to resolve the issue by updating the Advanced Email Security Settings.
For Salesforce to accept an email with Advanced Email Security Settings enabled, the user's email server must support at least one of the following protocols: SPF (Sender Policy Framework), Sender ID, or DomainKeys Identified Mail (DKIM). When the server passes at least one of these protocols, Salesforce processes the email and adds it to the record.
If the email server does not support any of these protocols, the recommended resolution is to disable the Advanced Email Security Settings.
After making this change, try to reproduce the issue and confirm that the email is now added to the Salesforce record or to the Unresolved Items queue.
Note: If you need to keep Advanced Email Security Settings enabled, engage your IT or Salesforce administrator team and reference the following resources for configuring DKIM Keys and SPF Records.
000384459

We use three kinds of cookies on our websites: required, functional, and advertising. You can choose whether functional and advertising cookies apply. Click on the different cookie categories to find out more about each category and to change the default settings.
Privacy Statement
Required cookies are necessary for basic website functionality. Some examples include: session cookies needed to transmit the website, authentication cookies, and security cookies.
Functional cookies enhance functions, performance, and services on the website. Some examples include: cookies used to analyze site traffic, cookies used for market research, and cookies used to display advertising that is not directed to a particular individual.
Advertising cookies track activity across websites in order to understand a viewer’s interests, and direct them specific marketing. Some examples include: cookies used for remarketing, or interest-based advertising.