Why Forwarding Emails Breaks Formatting and Causes Duplication (and How to Fix It)

Estimated reading time: 6 minutes

Forwarding an email seems like one of the simplest actions you can take in your inbox. Just click Forward, add a recipient, and hit Send. But beneath that familiar action lies a surprisingly complex process involving HTML code, authentication headers, and multiple server interactions. This process can easily distort your email’s layout, create duplicates, or harm your deliverability without you realizing it.

Understanding why this happens is essential for anyone managing professional communication, business domains, or free email forwarding services. Let’s explore how forwarding actually works, why it often causes formatting issues or duplication, and how you can avoid them to keep your inbox clean.

What Is Email Forwarding?

At its core, email forwarding is the process of redirecting incoming emails to another mailbox, either automatically or manually. This feature is commonly used for convenience. For example, to forward work messages to a personal inbox or to manage multiple email addresses under one account.

There are two main types of forwarding:

• Manual forwarding: You open an email and click Forward. This creates a new message that includes the content of the original email. You can edit, remove, or add recipients before sending.
  
• Automatic forwarding: You configure rules within your provider, like how to set up email forwarding in Gmail or Outlook email forwarding, so that every incoming email is instantly redirected to another address.

While this functionality is useful, it often introduces invisible changes (modifying headers, stripping code, or re-encoding attachments) that can break your email’s appearance or trigger duplication.

Why Forwarding Disrupts Formatting

Email formatting issues occur because forwarding forces your email client to reinterpret the existing message’s HTML and CSS. Most modern marketing or transactional emails use carefully structured HTML, inline styles, and embedded images to look perfect across devices. But when you forward these messages, several things can go wrong:

1. Rewritten HTML structure.
   Many email clients (especially Outlook) wrap the original HTML message in a new layer of code. This can break tables, collapse spacing, or change the alignment of text and images. What once looked perfect in your inbox may appear distorted or disjointed after forwarding.
   
2. Stripped CSS or external styles.
   Forwarding often removes or simplifies the CSS used for styling. For instance, Gmail converts unsupported CSS into plain text, which causes fonts, colors, and buttons to appear incorrectly.
   
3. Broken images and links.
   When forwarding, embedded images may no longer reference the original server path. Instead, they can be transformed into local or temporary files, making them disappear when viewed by the recipient.
   
4. Encoding issues.
   Some clients modify the encoding format of forwarded emails, corrupting special characters or emojis.
   
5. Reformatted text blocks.
   Forwarding adds quotation lines or indents that can distort message flow. If the email already uses a nested layout (like a newsletter or transactional receipt), this can make it nearly unreadable.

As a result, when forwarding beautifully designed emails, the outcome can look broken, cluttered, or unprofessional.

Why Forwarding Can Cause Duplication

Email duplication is another common problem caused by forwarding. It happens when email servers process the same message multiple times due to overlapping rules or misconfigurations.

1. Looping rules.
   If you configure email forwarding in Gmail to send to an address that also forwards back to the original, the two accounts can start endlessly forwarding messages to each other. This creates infinite loops of the same message filling both inboxes.
   
2. Group alias forwarding.
   When multiple recipients share a forwarding alias, everyone receives a copy. If one person replies or forwards again, others can receive duplicates of the same thread.
   
3. Mailbox mirroring and syncing tools
   Third-party synchronization services can store duplicates when a forwarded message is marked as new each time it enters a mailbox.

These loops and replications waste storage, confuse users, and, more critically, affect your deliverability reputation. When email servers detect repetitive forwarding or duplicate headers, they might flag your messages as spam or block future deliveries.

How Forwarding Affects Deliverability and Security

The technical side of forwarding can interfere with authentication mechanisms like SPF, DKIM, and DMARC — the trio of protocols that prove an email’s legitimacy.

• SPF (Sender Policy Framework): Verifies whether the server sending the email is authorized by the domain. When you forward an email, it’s now sent by a different server (Gmail, Outlook), not the original domain. This can cause SPF checks to fail.
  
• DKIM (DomainKeys Identified Mail): Ensures that the email hasn’t been tampered with in transit. Forwarding can sometimes alter message headers or body content, invalidating the DKIM signature.
  
• DMARC (Domain-based Message Authentication, Reporting & Conformance): Combines SPF and DKIM results. If either fails during forwarding, the recipient’s mail server may reject or quarantine the message.

For businesses, this means forwarded messages may land in spam folders or get blocked entirely, especially when using Google Workspace email forwarding or Outlook email forwarding for official communication.

To prevent these issues, you should regularly test deliverability and authentication alignment. With GlockApps, your emails will continue reaching their audience instead of vanishing into spam folders.

How to Minimize Formatting and Duplication Issues

You can’t control how every email client interprets forwarding, but you can reduce the risks:

• Forward as an attachment instead of inline.
  Most email platforms allow you to forward messages as .eml attachments. This preserves the original headers and formatting.
  
• Use plain-text forwarding for simple messages.
  Stripping HTML removes the risk of broken code. For essential communications, simplicity improves clarity.
  
• Limit forwarding rules.
  Avoid redundant or circular forwarding chains. Test each route to ensure it ends where you expect.
  
• Monitor your domain’s deliverability health.
  Use GlockApps DMARC Analyzer to track DMARC performance, detect failures caused by forwarding, and protect your domain from spoofing or phishing attempts.

• Check your HTML email design before forwarding
  If you’re forwarding marketing campaigns, use responsive and inlined CSS templates to minimize layout shifts.

Conclusion

Forwarding emails may appear harmless, but it’s one of the most common causes of broken formatting, duplicate messages, and deliverability issues. Each time you forward an email, the content is reprocessed, often stripped of its structure and authentication.

For individuals, that means messy inboxes and unreadable threads. For businesses, it can mean lost messages, damaged sender reputation, and missed opportunities.

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