I use Mailstore Home to backup my Gmail account but it stopped working last month, giving the following error, preventing it accessing my Gmail account:

 

An error has occurred.

 

The SSL/TLS certificate verification failed. In order to skip the certificate verification, please enable the "Accept all certificates” option. Details: Unable to perform revocation check of the server certificate.

 

If I pause Kaspersky, it works correctly, so it looks like Kaspersky is blocking access for some reason.

(The Mailstore Home error message isn’t quite correct as there is no "Accept all certificates” option. 

Is there a setting in Kaspersky that I can change to fix this?

I’m running Kaspersky Internet Security 21.2.16.590 (b)

@AlanH Welcome. Did you try “Do not scan encrypted connections” ?

Thanks for the quick reply, Berny.

Just tried that and it allows Mailstore to work. After Mailstore stared checking for emails, I switched Kaspersky back to “Scan encrypted connections upon request from protection components” and Mailstore kept on running so I assume it only checks just at the start.

However, disabling the scan of encrypted connections isn’t a long-term fix as it disables too many other services. Can I add gmail.com as an exclusion?

@AlanH You are welcome. Please see https://support.kaspersky.com/common/error/other/13720

 

@AlanH Please see https://support.kaspersky.com/common/error/other/12489#block4

Thanks again, Berny.

I added gmail.com as an exclusion but I get the same error. I also tried imap.gmail.com (which is the mail server) and that also gives the same error.

Any other suggestions?

@AlanH Can you please post a screenshot from the error.

The error Mailstore throws is as in my first message. I have been told that the "Accept all certificates” option is not something that is applicable because it’s not an option on Mailstore Home/Gmail.

 

The Report Error… link leads to a page of diagnostic information but not sure it’s of much use to you (personal information redacted):

 

The SSL/TLS certificate verification failed. In order to skip the certificate verification, please enable the "Accept all certificates" option. Details: Unable to perform revocation check of the server certificate.

*** Environment ***

Product Name:        MailStore Home
Product Version:     13.0.3.20071
App Build Date:      2020-09-07
App Copyright:       Copyright (c) 2005-2020 MailStore Software GmbH
App Description:     
App Dir:             C:\Program Files (x86)\MailStore\MailStore Home
App File Name:       C:\Program Files (x86)\MailStore\MailStore Home\MailStoreHome.exe
App Title:           MailStore
Operating System:    Windows 10 Home x64
OS Bitness:          x64
Process Bitness:     x86
Is Mono:             False
Is Windows:          True
.NET 4 Release Key:  528372
.NET CLR Version:    4.0.30319.42000
Proc Culture:        en-GB
Proc UI Culture:     en-GB
Machine Name:        DESKTOP-xxxxx
User Domain Name:    DESKTOP-xxxxx
User Name:           xxxxxx
License ID:          xxxxxxxxxxxxxxxxxx

*** Exception Details ***

#DG.#yI: The SSL/TLS certificate verification failed. In order to skip the certificate verification, please enable the "Accept all certificates" option. Details: Unable to perform revocation check of the server certificate.

Server stack trace: 
   at #DG.#lN.#4Ke(String #wm, Char #g, String #3bb, PropertySet #4bb, Boolean #wQf)
   at #9t.#qD.#6yl(#RI #pTm)
   at MailStore.Common.Progress.ProgressDialog.#6I()
   at System.Runtime.Remoting.Messaging.StackBuilderSink._PrivateProcessMessage(IntPtr md, Object[] args, Object server, Object[]& outArgs)
   at System.Runtime.Remoting.Messaging.StackBuilderSink.AsyncProcessMessage(IMessage msg, IMessageSink replySink)

Exception rethrown at [0]: 
   at System.Runtime.Remoting.Proxies.RealProxy.EndInvokeHelper(Message reqMsg, Boolean bProxyCase)
   at System.Runtime.Remoting.Proxies.RemotingProxy.Invoke(Object NotUsed, MessageData& msgData)
   at System.Action.EndInvoke(IAsyncResult result)
   at MailStore.Common.Progress.ProgressDialog.#5I(IWin32Window #yk, String #qOf, #VX #tK, ProgressDialogMethod #RY)
   at #9t.#qD.#cJk()
   at #9t.#qD.#yKe()

*** Server Exception Info ***
Rebex.Net.TlsException: Unable to perform revocation check of the server certificate.
   at Rebex.Net.Imap.TryUpgrade(TlsParameters parameters, Boolean failOnClosed)
   at Rebex.Net.Imap.ConnectSync(String serverName, Int32 serverPort, TlsParameters parameters, SslMode security)
   at Rebex.Net.Imap.ConnectInternal(String serverName, Int32 serverPort, TlsParameters parameters, SslMode security)
   at #UAb.#1rg.#Trg()
   at #UAb.#1rg..ctor(String #en, Int32 #V9, String #gQf, Int32 #0Fb, ICertificateVerifier #b4n, #29g #Tlf, #tG #c4n, #8lg #p3n)
   at MailStore.Connectors.Mailboxes.ImapMailbox..ctor(String serverName, Int32 port, String protocol, Int32 timeout, ICertificateVerifier certificateVerifier, #eah mailboxType, #29g authentication, Boolean writeConnectionDebugLog, #8lg connectionMonitor, #Lpg mailboxCache)
   at #UAb.#hHb.#dHb(#SEb #cXb)
   at #UAb.#hHb.#1Gb(#SEb #cXb)
   at #lFb.#sFb.#rFb()
   at MailStore.ServiceFoundation.MailStoreServiceFoundation.#TSe(#9Qe #Rmc, String #wm, Char #g, String #3bb, PropertySet #4bb, Boolean #wQf)
   at #DG.#7Qe.#4Ke(String #wm, Char #g, String #3bb, PropertySet #4bb, Boolean #wQf)
   at #DG.#mN.Invoke(#BL #KQf, String #RY, BinaryReader #wW, BinaryWriter #7P)

*** Inner Exception ***
Rebex.Net.TlsException: Unable to perform revocation check of the server certificate.
   at Rebex.Net.TlsBaseSync.Process()
   at Rebex.Net.TlsBaseSync.Negotiate()
   at Rebex.Net.Tls12SocketSync.Negotiate()
   at Rebex.Net.TlsSocket.Negotiate()
   at Rebex.Net.ImapSocket.Upgrade(TlsParameters parameters)
   at Rebex.Net.Imap.TryUpgrade(TlsParameters parameters, Boolean failOnClosed)

*** Inner Exception ***
Rebex.Net.TlsException: Unable to perform revocation check of the server certificate.
   at Rebex.Net.TlsHandshakeSync.VerifyCertificate(String commonName, CertificateChain certificate)
   at Rebex.Net.TlsHandshakeSync.OnHandshakeReceivedClient(Byte[] buffer, Int32 offset, Int32 count, Handshake h)
   at Rebex.Net.TlsHandshakeSync.OnHandshakeReceived(Byte[] buffer, Int32 offset, Int32 count)
   at Rebex.Net.TlsBaseSync.ProcessHandshake(Byte[] buffer, Int32 offset, Int32 length)
   at Rebex.Net.TlsBaseSync.Process()

I have been trying various settings and have set Mailstore as a trusted application with only the ‘Do not scan encrypted traffic’ exclusion enabled and that now works.

This seems like a viable solution to the issue - are there any disadvantages to doing this?

Hello, @AlanH ,
Yes, this is a normal solution, there is only one drawback, the downloaded files are not checked by the web antivirus in this case, but when the files are opened, they are checked by other antivirus components. Try the recommendations in this article:  https://support.kaspersky.com/common/compatibility/13529