apt install msmtp msmtp-mta

default: hogehoge@hogehoge.hoge

# Example for a system wide configuration file

# A system wide configuration file is optional.
# If it exists, it usually defines a default account.
# This allows msmtp to be used like /usr/sbin/sendmail.
account default

# The SMTP smarthost.
host hogehoge.hoge
port 587
from hogehoge@hogehoge.hoge
user hogehoge@hogehoge.hoge
password password
auth on

# Construct envelope-from addresses of the form "user@oursite.example".
#auto_from on
#maildomain oursite.example

# Use TLS.
tls on
tls_trust_file /etc/ssl/certs/ca-certificates.crt

# Syslog logging with facility LOG_MAIL instead of the default LOG_USER.
syslog LOG_MAIL

aliases /etc/aliases

doveadm pw -s SSHA256
#ハッシュを通したパスワードを得る
vim.tiny /etc/dovecot/users
vim.tiny /etc/postfix/virtual
#周りに合わせて適当にユーザーを追加
postmap /etc/postfix/virtual
#そして、dovecotとpostfixをrestartしたりreloadしたりする