/etc/hostname の内容を、ドメイン名以外で運用しています。

メール送信のためPostfixをインストールし、設定ファイルmain.cfで
myhostname = mail.ドメイン名.com
としましたが、送信したメールには反映されず、/etc/hostnameの内容が
送信元アドレスとなってしまいます。

どの様に、修正すれば良いでしょうか？

＜追加情報＞
postconf -nの結果

$ postconf -n
alias_database = hash:/etc/postfix/aliases
alias_maps = hash:/etc/postfix/aliases
append_dot_mydomain = no
biff = no
compatibility_level = 2
inet_interfaces = all
inet_protocols = all
mailbox_size_limit = 0
mydestination = $myhostname, localhost, localhost.localdomaina, $mydomain
mydomain = ******.com
myhostname = mail.******.com
mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128
myorigin = $myhostname
readme_directory = no
recipient_delimiter = +
relayhost =
smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache
smtpd_banner = $myhostname ESMTP unknown
smtpd_relay_restrictions = permit_mynetworks permit_sasl_authenticated defer_unauth_destination
smtpd_tls_cert_file = /etc/ssl/certs/ssl-cert-snakeoil.pem
smtpd_tls_key_file = /etc/ssl/private/ssl-cert-snakeoil.key
smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache
smtpd_use_tls = yes

mail.logの内容です

$ cat /var/log/mail.log
Apr 14 12:20:26 Debian postfix/qmgr[595]: 91EBB1FC38: from=<user01@Debian>, size=335, nrcpt=1 (queue active)
Apr 14 12:20:26 Debian postfix/smtp[739]: 91EBB1FC38: to=<送信先@provider.ne.jp>, relay=mx.provider.ne.jp[219.111.22.333]:25, delay=327, delays=327/0.19/0.07/0.18, dsn=4.1.8, status=deferred (host mx.provider.ne.jp[219.111.22.333] said: 450 4.1.8 <user01@Debian>: Sender address rejected: Domain not found (in reply to RCPT TO command))
Apr 14 12:21:02 Debian postfix/pickup[594]: E5F4B1FC3A: uid=1000 from=<user01@Debian>
Apr 14 12:21:02 Debian postfix/cleanup[744]: E5F4B1FC3A: message-id=<20180414032102.E5F4B1FC3A@mail.******.com>
Apr 14 12:21:02 Debian postfix/qmgr[595]: E5F4B1FC3A: from=<user01@Debian>, size=333, nrcpt=1 (queue active)
Apr 14 12:21:03 Debian postfix/smtp[739]: E5F4B1FC3A: to=<送信先@provider.ne.jp>, relay=mx.provider.ne.jp[219.111.22.333]:25, delay=0.69, delays=0.17/0.01/0.06/0.45, dsn=4.1.8, status=deferred (host mx.provider.ne.jp[219.111.22.333] said: 450 4.1.8 <user01@Debian>: Sender address rejected: Domain not found (in reply to RCPT TO command))