O mpack usa o que é conhecido como o sendmail (API compatível) para funcionar.
Usuários não-root não podem alterar o endereço De das mensagens; apenas root é permitido fazer isso.
Configurações explícitas em todo o servidor no seu MTA de escolha (ssmtp, sendmail, postfix) também são capazes de fazer isso.
Com o sendmail você pode mudar o globalmente de acordo com estas instruções de link
With sendmail, you can change both the domain and username on a case-by-case basis using the genericstable feature:
1) Add these statements to your /etc/mail/sendmail.mc file to activate the feature:
FEATURE('genericstable','hash -o /etc/mail/genericstable.db')dnl GENERICS_DOMAIN_FILE('/etc/mail/generics-domains')dnl
2) Create a /etc/mail/generics-domains file that is just a list of all the domains that should be inspected. Make sure the file includes your server's canonical domain name, which you can obtain using the command:
sendmail -bt -d0.1 </dev/null
Here is a sample /etc/mail/generics-domains file:
my-site.com another-site.com bigboy.my-site.com
3) Create your /etc/mail/genericstable file. First sendmail searches the /etc/mail/generics-domains file for a list of domains to reverse map. It then looks at the /etc/mail/genericstable file for an individual email address from a matching domain. The format of the file is
linux-username [email protected]
Here is an example:
alert [email protected] peter [email protected] apache [email protected]