Cannot setup inbound email


We are trying to configure email marketing on suiteCRM, we can create campaign there is no problem until we got to select an email to send the campaign.

I tried to setup email through the wizard but each time I finally got a time out error.

I looked for some informations into log, but nothing could help me.

Has someone already get this error and can teach me how to avoid it ?

We are running SuiteCrm 7.2.2 on an ubuntu server, using nginx server.