Hi,

I have a problem in sending mail in a website developed using DNN 7.3.1, This problem raised when we have changed the SMTP configurations in host settings for a real one instead of those I was using during development. 

The problem is that when I these new SMTP settings in host settings it succeed and it send mail, also there are some functionalities in site like sending newsletter is working well and also send mail in both synchronous and Asynchronous ways. But when I try to register with a valid email and wait for a an activation mail as the way of registration used in that DNN website is  "Verified', No email is sent an there is an exception logged in event viewer with the following details:

I have argued too much with Mail server I am using smtp mail from, but they ensure that there are no missing configurations or permissions needed from their side and also I am confused about the success of sending mail in some operation and others not.

So kindly can I get an explanation for this unusual behavior and guide me to can discover the main cause of this issue?

Best Regards

Thanks for your reply, but I want to know if this rely permission mean that I must use basic settings to provide user name and password for that smtp mail server or is it related to something else from their side?

Another thing I want to clarify, is that I have made a small website has one form for sending mail, and used that SMTP settings which is not working in my dnn website but it has sent mails successfully for any mails, so is there any more permission needed to can accomplish this from dnn website?

And why mails are sent from newsletters but cou'dn't be send from registration as an example?

we have tested smtp used via https://pingability.com/smtptest.jsp, and it succeed also!

Please help me to can fix this issue

Thanks for you reply,

Actually mail server providers are confirming that there is not any problem with their permissions and also tried to register using the same account as smtp user name provided and also failed to send mail also it is in the same domain, 

And also there is an external website I have built to send mails only using that SMTP configurations and it succeed!

I couldn't reach to the main cause of the problem, to can find the solution, Kindly provide me with more details.