Monday, February 8, 2021

How to check Outlook desktop app account connection problems with or blocked, stopped, not working, authentication problems

Recently my Kasperksy VPN IP addresse range has been blocked by Microsoft Endpoint protection uses the list, which blocked Kaspersky's address ranges. 

Here's how to check if your VPN blocks your connectivity to your mail server. 

1) Run Cmd.exe

2) Issue nslookup  (while command while connected with your vpn)

3) Type set type = mx (we going to find the mail server record (mx) for this url)

4)  Use domain for you email address ( domain is


Default Server:

> set type=mx

Non-authoritative answer:     MX preference = 5, mail exchanger =

4) Grab mail exchanger value "", 

this is your SMTP  (Simple Mail Transfer Protocol) server address for 

For Outlook, aliases are also addresses are, etc.

5) Exit (Ctrl-c)

6) ping 

Pinging [] with 32 bytes of data:
Request timed out.
Request timed out.
Request timed out.
Request timed out.

Ping statistics for
    Packets: Sent = 4, Received = 0, Lost = 4 (100% loss),

Non-authoritative answer:     MX preference = 5, mail exchanger =

Seems it's not reachable by ping.

Well,  let's try with telnet to test this SMTP server, on standard SMTP port 25. 

This is standard way administrators use to test their mail servers. 

7) Issue telnet 25

Returns he its back.....okay we are in
220 Microsoft ESMTP MAIL Service ready at Mon, 8 Feb 2021 20:59:11 +0000

8) Issue EHLO or HELO 

EHLO Hello []
250-SIZE 49283072

9) Issue MAIL FROM:

550 5.7.1 Service unavailable, Client host [] blocked using Spamhaus.
To request removal from this list see]

10) Kasperky VPN Address blocked by

BTW a result and email address check would be return the following, this is using google mail server.

MAIL FROM from SMTP Server : 250 2.1.0 OK m22si19950956pgu.215 - gsmtp
RCPT TO from SMTP Server : 250 2.1.5 OK m22si19950956pgu.215 - gsmtp

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