Update VPN

[Norbert_Telle]

Hallo zusammen,

ich möchte Sie auf ein Problem aufmerksam machen, das nach einem aktuellen Update von Norton Secure VPN aufgetreten ist.

Nach dem Update kann Microsoft Outlook 365 (klassisches Outlook) keine E-Mails mehr über ein Telekom POP/SMTP-Konto versenden.

Verwendete Version:

• Microsoft Outlook 365

• Version 2606

• Build 16.0.20131.20112 (32 Bit)

Fehlerbild:

• E-Mail-Empfang funktioniert weiterhin.

• Versand über Outlook funktioniert nur, wenn Norton Secure VPN deaktiviert ist.

• Versand über das Telekom-Webmail funktioniert jederzeit problemlos.

• Mit aktiviertem VPN erscheinen die Outlook-Fehler 0x800CCC0F bzw. 0x800CCC67.

Bereits durchgeführte Tests:

• SMTP-Port 465 (SSL/TLS) getestet.

• SMTP-Port 587 (STARTTLS) getestet.

• SMTP-Authentifizierung geprüft.

• Outlook als VPN-Ausnahme hinzugefügt (klassisches Outlook und neues Outlook) → ohne Erfolg.

• DNS-Auflösung und Netzwerkverbindung geprüft.

• SMTP-Server ist erreichbar.

• Outlook-Einstellungen geprüft.

• Telekom-Konto und Passwort geprüft.

Ergebnis:
Sobald Norton Secure VPN deaktiviert wird, können E-Mails sofort wieder versendet werden.

Das Verhalten ist jederzeit reproduzierbar und trat erst nach dem VPN-Update auf.

Ich würde mich freuen, wenn Sie dieses Verhalten prüfen könnten.

Vielen Dank und freundliche Grüße

Norbert Telle

[bjm]

@Norbert_Telle

Hello everyone,

I would like to draw your attention to a problem that has occurred after a recent update of Norton Secure VPN .

After the update , Microsoft Outlook 365 (classic Outlook) can no longer send emails via a Telekom POP/SMTP account .

Version used:

• Microsoft Outlook 365
• Version 2606
• Build 16.0.20131.20112 (32 bit)

Error pattern:

• Email reception still works.
• Sending via Outlook only works if Norton Secure VPN is disabled.
• Sending via Telekom webmail works without any problems at any time.
• With VPN enabled, Outlook errors 0x800CCC0F and 0x800CCC67 appear.

Tests already conducted:

• SMTP port 465 (SSL/TLS) tested.
• SMTP port 587 (STARTTLS) tested.
• SMTP authentication verified.
• Added Outlook as a VPN exception (classic Outlook and new Outlook) → without success.
• DNS resolution and network connection have been checked.
• The SMTP server is reachable.
• Outlook settings checked.
• Telekom account and password verified.

Result:
Once Norton Secure VPN is deactivated, emails can be sent again immediately.

The behavior is reproducible at any time and only occurred after the VPN update.

I would appreciate it if you could investigate this behavior.

Thank you very much and best regards

Norbert Telle

Hello @Norbert_Telle

The recent update to Norton Secure VPN has introduced a routing conflict or automated port block that prevents classic Microsoft Outlook 365 from communicating with the Telekom SMTP server, resulting in errors 0x800CCC0F and 0x800CCC67. Because you have already thoroughly eliminated basic configuration errors, this issue points to how the updated VPN driver handles mail server protocols or a failure in the application-based Split Tunneling feature.

Why This Is Happening

• Telekom IP Blacklisting: Many major ISPs like Deutsche Telekom actively block or reject SMTP traffic coming from known VPN data center IP addresses to minimize spam. When the VPN is active, your connection appears to originate from a shared VPN IP, causing Telekom’s security system to drop your outbound connection.
• Broken Split Tunneling Path: Classic Outlook is a 32-bit application on your system, but it relies on cross-process networking components. Even if you exclude outlook.exe, the underlying network requests may still be forced through the VPN tunnel by Norton’s updated network driver.
• Port and Protocol Restrictions: The update may have restricted generic outgoing TCP traffic on ports 465 and 587 across its virtual adapters.

To resolve this behavior, implement the following advanced troubleshooting steps:

1. Fix Split Tunneling by Path Disambiguation
   Because excluding the generic Outlook shortcut often fails after updates, you must manually point Norton specifically to the exact 32-bit executable:

2. Completely turn off the Norton Secure VPN.

3. Open Norton and go to the Split Tunneling preferences.

4. Remove your existing Outlook exceptions.

5. Click Add Application and manually navigate to the exact 32-bit installation folder:
   C:\Program Files (x86)\Microsoft Office\root\Office16\OUTLOOK.EXE

6. Save the configuration, restart your computer, turn the VPN back on, and attempt a send test.

7. Switch the VPN Protocol
   The updated version of Norton Secure VPN utilizes a few different routing mechanisms. Forcing a change can alter how email headers are packed:

8. Open your Norton app interface and select Settings.

9. Navigate to VPN Preferences and locate VPN Protocol settings.

10. Switch from the default protocol to Mimic (Norton’s stealth protocol designed to bypass ISP blocks) or WireGuard/OpenVPN.

11. Reconnect the VPN and test your outbox.

12. Exclude Telekom Mail Server via URL or IP (Alternative Bypass)
    If your version of Norton allows for URL/Domain-based split tunneling alongside application-based exclusions, add the Telekom mail server directly:

• Add securesmtp.t-online.de to the exclusion list.
• This forces any background process attempting to reach Telekom’s mail servers to completely bypass the VPN tunnel, regardless of whether it is triggered by Outlook, a script, or a background process.

4. Increase Outlook Server Timeouts
   A common side effect of the new VPN network driver is increased latency during the security handshake, which trips errors 0x800CCC0F and 0x800CCC67 before the transmission completes.

5. Inside classic Outlook, go to File > Account Settings > Account Settings.

6. Select your Telekom account and click Change.

7. Click More Settings and navigate to the Advanced tab.

8. Look for the Server Timeouts slider and increase it from the short default to 2 or 3 minutes.

9. Click OK, save the settings, and restart Outlook

Because you have clearly demonstrated that this behavior is highly reproducible and uniquely triggered by the updated VPN version, it is likely a bug within Norton’s virtual adapter driver. Please use the built-in Feedback loop inside your Norton Secure VPN dashboard to submit these technical metrics (specifically mentioning your 32-bit architecture and the exact Outlook build) so their development team can deploy a hotfix.

AI sourced content may make mistakes

[Norbert_Telle]

Nachtrag

Das Problem konnte letztlich behoben werden.

Die vorhandene Outlook-Ausnahme musste vollständig gelöscht und anschließend neu angelegt werden.

Eine bereits vorhandene Ausnahme wurde nach dem VPN-Update offensichtlich nicht mehr korrekt verarbeitet.

Nach dem Neuerstellen der Ausnahme funktioniert Outlook auch bei aktiviertem VPN wieder fehlerfrei.

Es wäre sinnvoll zu prüfen, ob bestehende Split-Tunneling-Regeln nach einem VPN-Update korrekt übernommen werden.

[bjm]

@Norbert_Telle

The problem was eventually resolved.

The existing Outlook exception had to be completely deleted and then recreated.

An existing exception was apparently no longer being processed correctly after the VPN update.

After recreating the exception, Outlook works flawlessly again, even with a VPN enabled.

It would be useful to check whether existing split tunneling rules are correctly applied after a VPN update.

Thanks for sharing your progress