dans /etc/postfix/main.cf, rajouter ces deux lignes qui empêcheront postfix de délivrer du mail sur l'internet, quel que soit les conditions du réseau :

inet_interfaces = localhost
mynetworks_style = host

J.

Subject:

Each user has a "Local" mailbox, a file at /var/spool/mail/. Normally, everything is configured correctly - with one exception: local mail for root. Without corrections, mail for root would arrive in a local mailbox for the user "postfix" and remain there unread.

Correction 1:

Edit your /etc/postfix/aliases file, make sure that the line root: postfix is replaced by a line root: (i.e. the name of a really existing user, who is meant to receive any mail sent to the user "root". The article mentions two other lines that need to be configured - I found that they already exist in out-of-the-box 10.2

The other instructions figuring in the article illustrate (a) how to make this configuration effective without rebooting the system (i.e. the "service postfix restart" command) and (b) how to verify that everything works correctly.

Correction 2:

kmail Screenshot more or less self-explaining: an account "local" is created, select as its locking method "FCNTL" or "Aucun" (I guess - I do not use kmail - in English that will be "None") - none is OK if you only expect to receive local mail very occasionally. FCNTL uses file locking, but the access rights to /var/spool/mail need to grant write access to everybody (dangerous) - the same problem as with Thunderbird.

Discussion (comments)

inet interfac = localhost mynetworks_style = (for use the address you configured for your network interface - nothing if you use zeroconf)

Hope that helps and is not too sloppy.