Can’t connect to server. 501 # 5.5.4 invalid argument

[towifi]

We have a user who is having tough time with Nexus 5 setup. We have checked the hostnames, ports and it all looks good. The problem seems to be with Outgoing server.


Error message: Can’t connect to server. 501 # 5.5.4 invalid argument

 

[towifi]

Yes we have.

 

[towifi]

Yes we did it without wifi.

 

[towifi]

Yes, works fine on other devices and outlook.

 

[towifi]

Yes they have.

 

[towifi]

What do you suggest?