Have you or your clients received a confusing "Sender Blocked" or "Delivery Failure" message when trying to send an email to your business address?

Often, these errors have nothing to do with your main inbox. Instead, they are caused by setting up an automatic forwarding rule in Plesk to "push" your business emails to a personal email account (like Gmail, Hotmail, or Yahoo).

This guide explains why forwarding causes these blocks, why modern security has changed how we check email, and how to set up your inbox correctly on your phone and computer.

How Email Forwarding Breaks (The Concept)

When someone emails your business address, and your Plesk mailbox is set to automatically forward a copy to a personal account, it triggers a chain of security checks across different mail networks.

[Original Sender] ──> [Your Rebel Inbox] (Delivered Successfully!)
                             │
                             └───(Auto-Forward Rule Triggers)───> [Outbound Security Relay] ──x [Personal Inbox (Gmail/Hotmail)] 
                                                                                                  (Blocked & Bounced!)

Why Did the Forward Get Blocked?

Why would a safe email get blocked simply because it was forwarded?

Modern email security relies heavily on domain authentication rules (known as SPF and DMARC). These rules tell the internet exactly which servers are authorized to send emails for a specific domain.

1. The Identity Crisis: When our server forwards the sender's email from your Plesk inbox to your personal Hotmail/Gmail inbox, the email still claims to be "From" the original sender.

2. The Security Check: Your personal email provider looks at the incoming message. It sees that the email claims to be from the sender's domain, but it is physically being sent by Rebel's servers.

3. The Block: Because Rebel is not listed on the sender's official list of authorized servers, your personal provider flags the email as "spoofed" (suspicious or spam).

4. The Reputation Protection: To prevent our server's reputation from being damaged by forwarding unauthenticated mail, our outbound security system (MailChannels) preemptively blocks the transfer.

Because the background forward failed, a "Delivery Failure" notification is automatically sent back to the original sender, leading them to believe their email never reached your business address at all (even though it did!).

How to Resolve This and Set Up Your Email Safely

To stop your clients from receiving these confusing bounce-backs, you must disable the auto-forwarder and choose a secure way to access your mail.

Step 1: Disable the Forwarder

1. Log into your Plesk Control Panel.

2. Go to Mail > Mail Accounts and click on your email address.

3. Click on the Forwarding tab.

4. Uncheck the Switch on mail forwarding box (or remove the external address) and click OK.

Step 2: Set Up Your Email on Your Devices

Since Google and other major providers have phased out the ability to "fetch" external POP3 mail into their desktop web-mail interfaces, here is how you should configure your email going forward:

On Your Mobile Phone or Tablet (Keep Using the Gmail/Outlook Interface!)

If you love using the Gmail or Outlook app, you can continue to do so on your phone or tablet.

• Do not use forwarding. Instead, simply add your business email directly to the Gmail or Outlook app as an IMAP account.
   

• The app will connect directly to our servers to securely display your mail. This is 100% secure, updates in real-time, and will never cause forwarding bounce-backs.

On Your Desktop Computer

Because web browsers cannot fetch IMAP/POP3 mail into a personal webmail account anymore, desktop users have three excellent options:

• Option A: Use a Dedicated Mail App (Recommended)

  Connect your business email directly to a desktop mail client like Thunderbird, Apple Mail, or Outlook for Desktop using IMAP. This keeps your mail secure and perfectly synced across your computer and phone.
   

• Option B: Access Plesk Webmail Directly

  You can log into your professional webmail portal directly in any browser (e.g., webmail.yourdomain.com) to manage your emails safely.
   

• Option C: Upgrade to Google Workspace or Microsoft 365

  If you absolutely want to use the Gmail or Outlook web interface on your desktop computer for your business email (info@yourdomain.com), the best path is upgrading to Google Workspace or Microsoft 365. This gives you the native web interface under your custom business domain—securely, professionally, and with zero forwarding loops!

Still Having Trouble? Send Us the ".EML" File!

If your clients are still seeing bounce-back errors and you aren't sure why, our support team can locate the exact block in the server logs. To do this, we need the raw headers of the bounce-back message, which are saved as an .EML file.

If your client or customer received the bounce-back error, ask them to export it and send it to you as an attachment. Here are the exact steps to do this on each major mail network:

For New Outlook (Windows & Web)

1. Select the bounce-back email from your message list so it opens in the reading pane.

2. Click on the More actions menu (the three horizontal dots ...) in the top right corner of the message header.

3. Select Save as. (Tip: You can also right-click the message directly in your inbox list and choose Save as).

4. Choose your destination folder on your computer and click Save. The email will save natively as an .eml file.

Important: Make sure you do not save or convert the file as a PDF! We need the original .eml formatting to analyze the raw email routing data.

• For more help, you can review the Official Microsoft Outlook Save Guide or refer to this step-by-step UseCarly Outlook Export Guide.

For Apple Mail (Mac OS)

1. Open the Apple Mail application on your Mac.

2. Click on the specific bounce-back email to highlight it.

3. Click on File in the top menu bar, then select Save As...

4. In the format dropdown, make sure the format is set to Raw Message Source.

5. Click Save. This saves the email directly as an .eml file.

• For a visual walkthrough of this process, please follow this Apple Mail EML Export Tutorial.

For Gmail (Web Browser)

1. Log into Gmail in your web browser.

2. Open the bounce-back email.

3. Click on the More button (the three vertical dots ⋮) located next to the Reply button.

4. Select Download message.

5. Gmail will automatically download the complete message file directly to your computer with the .eml extension.

• For a detailed breakdown of this method, check out the SysTools Gmail to EML Export Guide.

Once you or your client have saved this file, simply attach it to your support request with us! Our engineers can analyze the raw security headers inside to pinpoint exactly what caused the block and get it resolved for you immediately!