Link to home
Start Free TrialLog in
Avatar of YasuYasu
YasuYasuFlag for New Zealand

asked on

Custom application can't send email internally but can send externally on exchange 2007


I have windows2008/exc2007 servers. we also have another windows 2008 running custom app for CRM/timesheet.
The custom app engineer has created alert system which send  email to a user internally. He could send the alert email to externally but couldn't send to internally.

What he wants to do is that the sender of the alert email will be his external email address and recipient address is internal domain user. when internal user reply to the alert email, it goes to his external address.

I have used telnet to send email internally from his external email address which is fine.

Is there any other thing I can check whether something blocking from the custom app apart from the app?
I have diabled firewall/ESET on the server running custom app but nothing changed.


Avatar of nitin_badhwar
Flag of United Arab Emirates image


If the Sender Server IP is already in the Exchange Relay List then address can be anything.....even like it doesn't matter ....
I suspect there is something in the custom mail content which is prevented by MS Outlook.
You can test this by using SMTP commands.

From source server:-

1-Telnet <Exchange server HUB Server address> 25

when it shows connected
2- type EHLO

3- Type Mail
It should reply Sender OK.

4- Then type rcpt to:<Your internal email address>
It should reply as Recipient OK

5-Type Data and pres enter.

6- Then type . and enter

You should receive email  recipient's outlook

Hope it helps

Avatar of YasuYasu


Hi Nitin,

The telnet works well.  it can send email to an internal user but custom app can't send to an internal user.

So I guess custom app is having a problem to send? as telnet works fine.
Is there other way that I  can confirm the custom app has a problem apart from telnet?

Avatar of nitin_badhwar
Flag of United Arab Emirates image

Link to home
This solution is only available to members.
To access this solution, you must be a member of Experts Exchange.
Start Free Trial
Hi Nition,

I haven't heard from app developer and I assume it was a problem on his side.  so thanks for your answer.