exchange 2010

having a exchange issue, i can send email out from my domain but cannot receive email in

my exchange setup:
spam firewall
front-end exchange server )transport  hub)
back-end exchange server (mailbox store)

just used MX Lookup  tool on internet and when i try to check my SMTP server settings , it times out
and cannot communicate or find the smtp server

so my question is> what is the most likely cause, i dont see the emails attemps on the spam firewall, which is the first thing the emails should hit when coming from internet

could it be the smtp connector on back-end server
Who is Participating?
Malli BoppeCommented:
Use to check your MX records and make sure that they are pointing to your public Ip.
Also do you a CAS role installed on one of the servers.If not you need to
Are MX record and A record setup as required?

This article should be able to add some insight
piyushranusriSystem Cloud SpecialistCommented:
please go through with this URL, it will check your prerequisite and issue as well as .
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porto111Author Commented:
my mx records are good but it fails on SMTP test
Sikhumbuzo NtsadaSenior IT TechnicianCommented:
Was it working fine?
Have you paid your hosting company?
porto111Author Commented:
it was working fine
What SMTP test you are referring ?
telnet your.mail.server 25 > is it OK?

Did you enable anonymous on the Default Receive connector ?
porto111Author Commented:
smtp test from "mx lookup" tool on internet
Malli BoppeCommented:
what happens when you try from
Lets clear things step by step.

In order to receive emails from external user you need to have Authenticated users checkbox selected on the Receive connector properties: Is it there?

Perform a telnet from External to your MX record and let know what happens.
If this ever worked then need to understand what changes took place post which things stopped working?
Steps for the telnet test would be as below

Step 1) Telnet “Ip address or mx record” 25
Step 2) Ehlo
Step 3) mail from : (or) mail from : <>
Step 4) rcpt to : (or) rcpt to : <>
Step 5) data
Step 6) “Type the text” (you can type anything like your doing in an email)
Step 7) . (Period)
* Hit enter key after completing every steps
* Wait for the server to respond and after pressing the enter key
* Backspace wont work, so if you make a mistake, press enter and retype the command from the beginning

Sometimes we have seen issues with AV used on Exchange servers so would also suggest to Try disabling the virus protection for some time and see the results. Ensure exchange directories are already excluded from being scanned
So you have a MX record created with ISP ... if not it wont work :( ... also get a PTR as some domains check and allow emails to its users.

Once you have that it will take about 24-72 hrs to get updated and then try with
Telnet “Ip address or mx record” 25

You should get a 220 banner and then you can try to drop an email.

Also remember that Anonymous users have to be checked on the permissions tab on the Receive connector in EMC on HUB.

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