Note: domainname —> replace with you domain name
sudo apt remove postfix && apt purge postfix
sudo apt install sendmail
cd /etc/mail
mkdir -m 700 -p /etc/mail/authinfo
nano /etc/mail/authinfo/authinfo
add line in that file
AuthInfo: “U:root@domainname.com” “I:root@domainname.com” “P: Email id Password”
Note: create name root email id in you email provider or user any already created email id
cd /etc/mail/authinfo
makemap hash auth-info < auth-info
Configure your sendmail.mc
Open /etc/mail/sendmail.mc file in your text-editor and copy the follow lines and paste before the first MAILER line:
dnl # Defining smtp Smarthost for sendmail
define(SMART_HOST',mail.domainname.com’)dnl
define(RELAY_MAILER_ARGS',TCP $h 587′)dnl
define(ESMTP_MAILER_ARGS',TCP $h 587′)dnl
FEATURE(authinfo',hash -o /etc/mail/authinfo/authinfo.db’)dnl
FEATURE(genericstable',hash -o /etc/mail/genericstable.db’)dnl
GENERICS_DOMAIN_FILE(/etc/mail/generics-domains')dnl
define(confAUTH_OPTIONS’, A p')dnl
TRUST_AUTH_MECH(EXTERNAL DIGEST-MD5 CRAM-MD5 LOGIN PLAIN’)dnl
define(confAUTH_MECHANISMS',EXTERNAL GSSAPI DIGEST-MD5 CRAM-MD5 LOGIN PLAIN’)dnl
dnl FEATURE(masquerade_entire_domain)dnl
dnl MASQUERADE_DOMAIN(localhost)dnl
dnl MASQUERADE_DOMAIN(localhost.localdomain)dnl
dnl MASQUERADE_DOMAIN(mydomainalias.com)dnl
dnl MASQUERADE_DOMAIN(mydomain.lan)dnl
dnl MASQUERADE_DOMAIN(domainname.io)dnl
MASQUERADE_AS(domainname.com')dnl
FEATURE(masquerade_envelope)dnl FEATURE(masquerade_entire_domain)dnl
MASQUERADE_DOMAIN(domainname.io)dnl define(MAIL_HUB’, domainname.com')dnl define(LOCAL_RELAY’, `domainname.com’)dnl
cd /etc/mail
m4 sendmail.mc > sendmail.cf
service sendmail restart
$ echo ‘e-Mail TEST’| mail -s TEST email@yourdomain.com