Why are employees not receiving emails sent to customers and employees when no bounces are reported?

When employees don't receive emails sent to both customers and employees, despite the absence of bounce reports, the issue often stems from internal email handling processes after the message is accepted by the receiving server. This includes a multitude of potential causes: overly aggressive or misconfigured internal spam filters, especially within platforms like O365, that discard emails based on specific rules or configurations (e.g., blocking emails seemingly originating from the company but not sent via authorized servers); incorrect internal email server settings impacting routing; stringent DMARC policies rejecting emails sent 'on behalf of' the company without proper authorization; email client-specific filtering behaviors; greylisting mechanisms causing significant delivery delays; domain or IP addresses appearing on blocklists; SPF record misconfigurations; a poor sender reputation leading to filtering; and overly broad application of list-unsubscribe headers inadvertently blocking internal employee emails. The key is the email made it to the internal system which means there is an internal setting blocking emails.

Employees may not be receiving emails sent to both customers and employees, despite no bounce reports, due to a variety of internal factors. These include overly aggressive internal spam filters or firewalls blocking legitimate emails, incorrect internal email server configurations (particularly mail routing), strict DMARC policies rejecting 'on behalf of' emails, email client-specific filtering rules, greylisting causing delays, misconfigured internal routing rules, or even simple errors like incorrect email addresses. Essentially, internal systems may be treating these emails as unwanted, or misdirecting them.

Emails failing to reach employees despite successful external delivery and no bounce reports often result from internal filtering mechanisms. Email systems accept the mail (hence no bounce), but internal spam filters, especially in systems like O365, might discard messages based on defined rules or misconfigurations, such as blocking emails using the company domain but not originating from its mail servers. Furthermore, overly aggressive list-unsubscribe headers can inadvertently block employees. Troubleshooting requires auditing internal filtering rules, contacting internal IT, and understanding that once a system accepts a message, its fate is beyond external visibility.

When employees don't receive emails despite customers doing so and no bounces occurring, several potential causes exist related to email security and configuration. Microsoft's Exchange Online Protection (EOP) may be filtering messages based on anti-spam policies, leading to quarantine. Google Workspace highlights the possibility of the domain being on a blocklist, necessitating checks and email log analysis. Furthermore, an improperly configured SPF record, as detailed in RFC documentation, can cause rejection. Finally, a poor sender reputation, as indicated by Cisco Talos, can trigger internal security systems to block or filter emails.