SMTP server integration

Not able to add email domain or email account,
We have a custom domain and custom smtp server which runs outlook.
This is the what it is showing

Please help me to solve this error.

Hi @Shivam.thaker,

Please check the whole post.

Maybe it becomes helpful to you.

Thank You!

Its not based on MS-365

How are you configuring it? You can share images

I have server Ip and port number.
Only these details are shared by the IT team.
Telnet with the server work shows a connection established.
I and return this string.

Note we have a custom exchange server on which Outlook works,
We are not using Microsoft Office 365 or any other service.

as mentioned by @max_morais_dmm I tried using smtp lib and it was able to successfully send the mail.

Which ports are you using?

Port 25

You are using domain or IP.
In Incoming Server and Outgoing Server you are using

Same IP & Port for Both Incoming and outgoing.

To send mail you must have a domain name.
You cannot add the same port in incoming and outgoing.
If it is POP3 the port is 110
If SMTP the port is 993
The port is 25, 465 if you use SSL and 587 if you don’t use SSL.