What problems can redundant email forwarding cause and how to fix it?
Matthew Whittaker
Co-founder & CTO, Suped
Published 8 Aug 2025
Updated 17 Aug 2025
9 min read
Email forwarding, at its core, is a simple mechanism designed to redirect incoming messages from one email address to another. It seems straightforward, a useful tool for consolidating inboxes or managing communication flow, especially for customer service or support departments. However, what happens when this seemingly innocuous feature becomes redundant, or when configurations inadvertently create a loop where an email address forwards to itself or creates multiple, unnecessary pathways for the same message?
The intention behind setting up redundant email forwarding might be benign, perhaps as a forgotten leftover from an old system migration or an attempt to ensure messages are never missed. But the reality is, such setups can introduce a host of unforeseen complications that impact not just deliverability, but also system performance, storage, and even your sender reputation.
I often see scenarios where an email alias or mailbox is configured to forward to multiple destinations, including, bizarrely, back to itself. This redundancy might seem harmless, but it can lead to a cascade of problems, from duplicate messages flooding inboxes to more severe issues like mail loops and diminished trust from receiving mail servers.
The pitfalls of unnecessary forwarding
One of the most immediate and noticeable problems caused by redundant email forwarding is the proliferation of duplicate messages. When an email is forwarded to multiple destinations, or worse, back to an address that then re-forwards it, recipients can end up seeing the same email appear in their inbox two, three, or even more times. This quickly leads to inbox clutter and frustration among users, diminishing the efficiency of communication and making it harder to track genuine, unique messages.
Beyond the annoyance of duplicates, redundant forwarding can create mail loops. This occurs when an email is continuously forwarded between two or more addresses, or an address forwards to itself, resulting in an endless cycle. These loops consume significant server resources, lead to delivery delays, and can even cause messages to bounce with errors like 'too many redirects' or 'excessive hops.' Such errors not only prevent legitimate emails from reaching their destination but can also signal suspicious activity to internet service providers (ISPs) and email service providers (ESPs).
Moreover, the increased volume of emails generated by these redundancies can negatively impact your sender reputation. If mail servers detect unusually high volumes of duplicate messages originating from your domain, they might flag your domain as a source of spam, leading to emails being sent to the junk folder or even being outright blocked. This affects your ability to reach recipients, regardless of the content or legitimacy of your messages. It is crucial to understand that consistent delivery to the inbox relies heavily on a clean sending history and a good reputation.
Redundant email forwarding: expected vs. actual
Expected forwarding
Clarity: One clear path for an email from source to final destination.
Efficiency: Messages arrive promptly with minimal server load.
Deliverability: High chance of inbox placement due to proper configuration.
Actual redundant forwarding
Duplication: Recipients get multiple copies of the same email.
Mail loops: Emails endlessly cycle, consuming server resources.
Lower deliverability: Increased bounces, spam folder placement, or blocklisting.
Authentication failures and deliverability impact
Beyond duplication and mail loops, redundant forwarding can severely undermine email authentication protocols like SPF, DKIM, and DMARC. When an email is forwarded, especially through multiple hops or different mail servers, its authentication headers can be altered or stripped. SPF (Sender Policy Framework) is particularly vulnerable, as it checks if an email originates from an IP address authorized by the sending domain's DNS records. Forwarding often changes the sending IP, causing SPF checks to fail.
DMARC (Domain-based Message Authentication, Reporting, and Conformance) relies on SPF and DKIM for alignment. If SPF fails due to forwarding, and DKIM isn't properly maintained or aligns with the forwarding path, DMARC validation can also fail. This is particularly problematic if your domain has a DMARC policy set to 'quarantine' or 'reject,' as legitimate forwarded emails might then be marked as spam or blocked entirely. To understand more about this, you can read our article on how email forwarding and DMARC policies affect email delivery.
The impact of these authentication failures isn't just theoretical, they directly affect your email deliverability. Receiving servers often use DMARC and SPF results to determine whether an email is legitimate or potential spam. Repeated failures can significantly lower your sender reputation, making it harder for all your emails to reach the inbox. This can lead to your domain or IP addresses ending up on email blocklists (or blacklists), further hindering your email campaigns and crucial communications. A detailed explanation of how email forwarding affects SPF, DKIM, and DMARC validation is available in our knowledge base.
The danger of DMARC failures with forwarding
When emails are redundantly forwarded, particularly across different mail systems, the original authentication (SPF and DKIM) can break. If your DMARC policy is set to `p=quarantine` or `p=reject`, these legitimate, but now unauthenticated, forwarded emails may be sent to spam or blocked entirely. This can lead to missed communications and impact your deliverability rates. For more on this, consult Google's best practices for forwarding email.
Practical steps to identify and fix redundant forwarding
To address redundant email forwarding, the first step is to identify where it is occurring. This often involves reviewing the forwarding rules set up for your email accounts, aliases, and mailboxes. Check your email client settings, such as Outlook or Gmail, for any configured auto-forwarding rules. For domain-level forwarding, you will need to access your hosting control panel, like cPanel, or your email service provider's administrative interface. Look for any rules that send emails back to the originating address or to an address that ultimately loops back.
Once identified, disable or modify any redundant forwarding rules. If an email address is forwarding to itself, remove that specific rule. If multiple forwards are sending to the same ultimate destination, consolidate them into a single, direct forward. This simplifies the mail flow and prevents unnecessary loops and duplication. In some cases, organizations might have internal mail flow rules or transport rules that create these redundancies. A thorough audit of these rules is also necessary to prevent issues.
Sometimes, the redundant forwarding might be a remnant of a previous setup that is no longer needed but was never deactivated. It is important to confirm with relevant stakeholders or IT administrators if any applications or services still rely on these specific forwarding configurations before making changes. Removing an active, but seemingly redundant, forward without proper checks could inadvertently break a critical system or communication channel.
This PowerShell command sets up a transport rule in Microsoft 365 Exchange that could help prevent certain types of forwarding loops for an email alias or mailbox, particularly for emails containing Fwd: in the subject line, by rejecting them and stopping further rule processing if they are forwarded back to the same address. You might also want to review our guide on common issues with emails being forwarded twice.
Maintaining healthy email forwarding practices
To prevent future issues, implement a clear policy for managing email forwarding within your organization. Instead of relying heavily on forwarding, consider using shared mailboxes or distribution lists for team-based communication. These options often provide better control over message flow, centralize access, and are less prone to the authentication pitfalls associated with traditional forwarding. They also simplify management and audit trails.
Regularly audit your email forwarding configurations. This means periodically checking all email addresses and aliases for any active forwarding rules and ensuring they are still necessary and correctly configured. An annual or semi-annual review can help catch redundant or outdated forwards before they start causing problems. Pay close attention to any bounce messages or delivery errors that might indicate a forwarding issue.
Also, consider the impact on your email authentication standards. While DMARC, SPF, and DKIM are crucial for validating your emails, forwarding can sometimes complicate their proper functioning. For situations where forwarding is unavoidable, ensure that your DMARC records are monitored. You can learn more about how to safely transition your DMARC policy to stronger enforcement like quarantine or reject policies. This proactive approach helps maintain a healthy email ecosystem for your domain.
Views from the trenches
Best practices
Always prefer shared mailboxes or distribution groups over individual forwarding rules for team communication.
Regularly audit all email forwarding configurations, at least once a year, to identify and remove outdated or redundant setups.
Test forwarding paths after making changes to ensure emails are delivered correctly and without duplication.
Ensure your email authentication records (SPF, DKIM, DMARC) are configured to minimize issues with legitimate forwarding.
Maintain minimal and direct forwarding paths to avoid complex mail loops and unnecessary server load.
Common pitfalls
Forgetting to deactivate old forwarding rules after a user or department changes email addresses or leaves.
Creating multiple forwarding rules that lead to the same destination, resulting in duplicate emails.
Not considering the impact of forwarding on SPF and DMARC, leading to authentication failures and spam placement.
Setting up forwarding loops where an email address forwards to itself or creates an infinite redirection.
Assuming all forwarded emails retain their original formatting and attachments, which can often be disrupted.
Expert tips
Use a DMARC monitoring tool to identify authentication failures caused by forwarding, especially when moving to a `p=quarantine` or `p=reject` policy.
For external forwarding to third-party services, explore vendor-specific integration methods that avoid direct email forwarding to maintain authentication.
Implement server-side mail flow rules or transport rules to catch and manage potential forwarding loops or excessive duplicates proactively.
Educate users on the proper use of email aliases versus forwarding to reduce the likelihood of self-inflicted issues.
When troubleshooting, check intermediate mail servers for any hidden forwarding rules or configurations that might be contributing to redundancy.
Marketer view
Marketer from Email Geeks says redundant forwarding can often stem from other applications that might need it, so it's essential to confirm if any external dependencies exist before removal.
2024-04-24 - Email Geeks
Expert view
Expert from Email Geeks says authentication can break depending on how forwarding is configured, which is a significant concern for deliverability.
2024-04-24 - Email Geeks
Ensuring smooth email flow
While email forwarding is a valuable feature, redundant configurations can create a complex web of problems impacting deliverability, resource consumption, and sender reputation. From annoying duplicate emails to critical authentication failures, the consequences of unmanaged forwarding can be significant. By understanding these issues, performing regular audits, and adopting best practices like using shared mailboxes or distribution lists, you can maintain a healthier email environment.
Proactive management of your email infrastructure, including forwarding rules, is paramount for ensuring your messages consistently reach their intended recipients without friction. This not only improves internal communication efficiency but also strengthens your domain's credibility with receiving mail servers, safeguarding your overall email deliverability.
Outlook or Gmail, for any configured auto-forwarding rules. For domain-level forwarding, you will need to access your hosting control panel, like cPanel, or your email service provider's administrative interface. Look for any rules that send emails back to the originating address or to an address that ultimately loops back.
