The first field of the setup is the recipient, ok, why the second field ask for a password ?
You need to specify a password for the account that you've entered in order to connect to the SMTP server. For example, if you enter email@example.com
then VEB will attempt to connect to gmail SMTP server under username credentials using the password form the second field.
There is another filed at the bottom, under SMTP server IP or DNS name, is that the filed for user name related to the upper password field ?
Correct. Those settings are needed only in case you want to specify custom SMTP settings.
It is like i had to give the recipient password this mean that recipient send a mail to himself, not from someone like a service mailbox for example.
That's correct - the account that is used to connect to SMTP is used to send a notification to the very same username that you've specified in the upper field.