No such host as


I’m using SuiteCRM.
Version 7.8.3
Sugar Version 6.5.24 (Build 509) (OS : Linux ubuntu 3.13.0)

When I’m going to setup incoming email account here Emails->Settings->Add->Mail Account Properties->Incoming Email(filled correct detail of gmail)-> Test Settings.

I’m getting this error:

[color=#ff0000]No such host as
Please check your settings and try again[/color]

How can I fix this issue?

Thanks in advance.

Maybe you can find some more info there.