Unable to use a SMTP server other than 3CX's

[AustinM95]

OS: Windows 10 Professional
License: Standard Annual 15.5

I'm unable to use the dropdown option to select my own SMTP server. It's grayed out. (See Picture).

This would be fine if the 3CX SMTP server worked. When I press TEST I receive the error "AuthenticationInvalidCredentials 5.7.0 Denied"

Need a solution ASAP!

 

[Saqqara]

check https://www.3cx.com/community/threa...red-annual-licensed-system.54862/#post-226228

 

[HRMNY]

Standard license does not allow for custom SMTP server. The error message is most likely a NAT issue, the source IP doesn't match that of your FQDN IP.

 

[StefanW]

the issue is that the IP you are sending from is not equal to the IP which is mapped to your FQDN.