Postfix and Outlook - SSL error

[lostinspace2011]

I have my postfix server configured and secured as far as I can tell. However when trying to send an email using Outlook or Windows Mail the following error is reported in the mail.log

[lostinspace2011]

I ended up resetting the windows firewall and this fixed the issue. Rather strange as this was on a fresh installation. Maybe removing McAffee did something to the firewall rules

[lostinspace2011]

Spoke too soon. While this seem to have addressed the problem in the short term. My issue came back. I think this is something on the windows side rather then postfix as it only happens from one computer. Another computer running windows 10 works without issues.

[lostinspace2011]

I made some further progress on this issue. The problem is only present when connected via WIFI. When using my ethernet port all emails are delivered as normal. I have

Reset the router
Verified there are no special rules configured on the router
Reset the windows firewall rules to default
Disabled the windows firewall
Used the McAffee removal tool to ensure there is nothing left behind
Changed my IP address
Switched between public and private network
Tried using an external SMTP service which presented the same failures.

So far none of these allow me to complete sending the message. The connection to the server is made, but as soon as the DATA section of the email is transmitted the connection is terminated. This seems to only happen when connected over WIFI.

[lostinspace2011]

https://answers.microsoft.com/en-us/msoffice/forum/all/outlook-2016-problem-sending-emails-error/db6e2794-ed89-44c0-9616-cbe563eeb6dc?page=2

It appears that the problem was caused by some Dell pre-installed software, which I had initially thought was a driver. It appears that the software is in fact not a driver, but a network management or quality of service type of software. The name of the application is SmartByte. In Windows Services it appears as “Rivet Dynamic Bandwidth Management” and “SmartByte Network Service”.

This software can be found in the Microsoft Store:

https://www.microsoft.com/en-au/p/smartbyte/9mwzs8xm2b89?activetab=pivot:overviewtab

From looking at other recent reports of this problem (easy to find when you know what you are looking for), this software needs to be disabled in Windows Services, not uninstalled. It appears that software will be automatically reinstalled during Windows or Dell software updates.

It would also appear that this problem only occurs over a WiFi connection using the Dell built in network card. If an Ethernet cable is used or an alternative USB WiFi adapter is used the problem doesn't appear to occur.

Now what I find is very strange is that the Thunderbird Email client didn't have any problems with this software, but Outlook did.

Additional references to this problem, which have very recently been published:
https://www.dell.com/community/Productivity-Software/0x800ccc0f-error-outlook-2019-works-wired-error-wireless/m-p/7186615
https://www.reddit.com/r/Dell/comments/abcwxc/smartbytes_prevented_outlook_from_sending_email/

As these references have been published very recently, it is entirely possible that a recent update has been issued for the SmartByte software that is causing this problem.

I suggest that Microsoft include in their Outlook trouble shooting guide to use an alternative network connection device, particularly Ethernet.

[lostinspace2011]

https://www.dell.com/community/Inspiron/Inspiron-G3-17-3779-Outlook-email-WiFi-can-t-send/td-p/7220911


Re: Inspiron G3 17-3779, Outlook email, WiFi can't send

We have confirmed that a large number of these problems are caused by using an outdated version of the Intel Wi-Fi driver. You can update your Intel Wi-Fi drivers to the latest version available by downloading and installing the appropriate package from Dell here – https://www.dell.com/support/home/us/en/19/drivers/driversdetails?driverid=vg6m5.

If that doesn't solve the issue for you, updating SmartByte from this location - https://www.dell.com/support/home/us/en/rc974514/drivers/driversdetails?driverid=mmvk6 - may help.

If you have any other issues with SmartByte, please tell us about it by submitting a ticket here - http://support.rivetnetworks.com/submit-a-ticket/

-- Anthony with Rivet Networks