Установка msmtprc

sudo apt-get install msmtp-mta ca-certificates
sudo nano /etc/msmtprc 
 
 defaults 
 tls on tls_starttls on tls_certcheck off tls_trust_file /etc/ssl/certs/ca-certificates.crt 
 account default host <smtp.example.net> port 465 auth on keepbcc on user <username@example.net> password <password> from <username@example.net> syslog LOG_MAIL 
 
 sudo nano /etc/php/7.4/apache2/php.ini 
 
 sendmail_path = /usr/bin/msmtp -t 
 
 echo "Test Mail." | msmtp -a default username@domain.com