Installed Premium but now cannot send emails via Mozilla Thunderbird

[JeffC]

I installed Kaspersky Premium yesterday (11 May 2023) but found that I cannot send emails via Mozilla Thunderbird client. Premium was the only configuration change made to my Windows 11 PC so I suspected it to be the cause.

Error was "Sending of the message failed.  The message could not be sent because the connection to outgoing server(SMTP) smtp.office365.com was lost in the middle of the transaction. Try again.

I stopped Premium, uninstalled it and downloaded my old AV (Kaspersky Total Security) but this is due to expire in 1 DAY!!  Emails now being sent OK.

I could not find a reported error with Premium/Thunderbird so I am posting on here in the hope the issue can be quickly resolved.

Any assistance asap will be appreciated.

 

[harlan4096]

Welcome to Kaspersky Community.

 

Go to Settings -> Security Settings -> Advanced Settings -> Network Settings ->Encrypted Connection Scan -> Trusted Addresses -> add Your email servers there.

[JeffC]

Thanks for the speedy response harlan4096. I assume you mean Settings in the Kaspersky program, in which case I cannot see Security Settings within Settings. Of course I am using Total Security now as I backed out Premium, so I cannot see what options may be available in Premium.

If I reinstall Premium and the fix you suggest doesn't work then I have a fair amount of activity to get back to a point where emails can be sent again ??

[JeffC]

Reinstalled Premium and amended the setting you suggested and emails now being sent successfully. Thanks harlan4096?

[harlan4096]

Great ?

[Cheeseus]

I appear to be having a similar problem but the proposed solution does not work.

I installed Kaspersky Plus a couple of days ago. Now I am unable to send emails from Thunderbird from my work account, which uses the outlook.office365.com server. I have added outlook.office365.com to "Trusted addresses", restarted Thunderburd several times, tried switching between the default "Use Windows certificate store (recommended)" and "Use Mozilla certificate store" (but I don't know what certificate to install manually.

When I click "Send", I am first prompted to select a certificate. I am offered an Adobe Content Certificate 10-6, Issuer: Adobe Intermediate CA 10-4, Valid from: 20.08.2018 to 18.08.2025. If I click "More choices", there's another one like the above but the numbers are "10-5" and "CA 10-3", the validity period is the same. (I don't understand what Adobe has got to do with Office 365.)

Whichever I select, when I click "Send", the "Sending message" dialogue just hangs there and nothing happens. Well, after 3–4 minutes, I got this: "Sending of the message failed. The message could not be sent because the connection to Outgoing server (SMTP) smtp.office365.com was lost in the middle of the transaction. Try again."

In the meantime, I am receiving emails for this account.

Please help as this is important and a bit urgent.

 

[harlan4096]

Do You have any Adobe product installed in Your system?

[Cheeseus]

7 minutes ago, harlan4096 said:

Do You have any Adobe product installed in Your system?

Yes, Adobe Acrobat and Adobe InDesign.

In the meantime, I followed the instructions to export the Kaspersky Root certificate and import it into Thunderbird – didn't help.

... Oh! I am unable to send emails from ANY of my email accounts in Thunderbird. This is a disaster.

Edited May 19, 2023 by Cheeseus

[harlan4096]

But are those Adobe product updated? Is that certificate from Adobe still valid in expiration?

[Cheeseus]

10 minutes ago, harlan4096 said:

But are those Adobe product updated? Is that certificate from Adobe still valid in expiration?

Yes, they are – I wrote the expiration date above (18.08.2025). But why are these certificates shown at all? What has Adobe got to do with Office 365 or Gmail or the other mail servers I am using. I can't send any emails now from any of the five email accounts I have in Thunderbird.

How can I disable Kaspersky from monitoring Thunderbird – I need to be able to send emails.

CORRECTION: I can't send emails only from my Gmail and from my Office 365 accounts. I was able to send emails from my other three accounts.

Edited May 19, 2023 by Cheeseus

[harlan4096]

I guess, but not sure, those certificates shouldn't be there... personally I would remove them, BUT it is not my system ?

[Cheeseus]

4 minutes ago, harlan4096 said:

I guess, but not sure, those certificates shouldn't be there... personally I would remove them, BUT it is not my system ?

Just got it to work! I had previously added "outlook.office365.com" to Trusted addresses. I now added "smtp.office365.com" and I was able to send a test email.

Sure, I can delete them, although I'm not quite sure how to do this.

Thank you for trying to help!

[harlan4096]

Great, but I thought You already added that server also to Trusted, in these cases You have to add the 2 servers (Delivery / Send) addresses in case are different outlook.office365.com / smtp.office365.com

[Cheeseus]

13 minutes ago, harlan4096 said:

Great, but I thought You already added that server also to Trusted, in these cases You have to add the 2 servers (Delivery / Send) addresses in case are different outlook.office365.com / smtp.office365.com

Yes, I'd initially added just the former. Adding the latter did the trick. I've also added smtp.gmail.com.