我最近在 Ubuntu 18.04 服务器上安装了 squirrelmail，主要遵循以下指南如何在 Ubuntu 18.04 上设置邮件服务器？
我可以使用浏览器登录，但是当尝试发送邮件时，我进入/var/lob/mail.log：
Mar 15 12:37:00 papa-legba postfix/smtpd[26002]: connect from localhost[127.0.0.1]
Mar 15 12:37:00 papa-legba postfix/smtpd[26002]: 8861A580AD5: client=localhost[127.0.0.1]
Mar 15 12:37:00 papa-legba postfix/cleanup[26005]: 8861A580AD5: message-id=<[email protected]>
Mar 15 12:37:00 papa-legba postfix/qmgr[24391]: 8861A580AD5: from=<[email protected]>, size=759, nrcpt=1 (queue active)
Mar 15 12:37:00 papa-legba postfix/smtpd[26002]: disconnect from localhost[127.0.0.1] ehlo=1 mail=1 rcpt=1 data=1 quit=1 commands=5
Mar 15 12:37:00 papa-legba postfix/local[26007]: 8861A580AD5: to=<[email protected]>, relay=local, delay=0.01, delays=0.01/0/0/0, dsn=2.0.0, status=sent (delivered to mailbox)
Mar 15 12:37:00 papa-legba postfix/qmgr[24391]: 8861A580AD5: removed
Mar 15 12:37:00 papa-legba dovecot: imap-login: Login: user=<mail_user>, method=PLAIN, rip=127.0.0.1, lip=127.0.0.1, mpid=26010, secured, session=<jYDRT+eg6tl/AAAB>
Mar 15 12:37:00 papa-legba dovecot: imap(mail_user): Logged out in=651 out=589
Mar 15 12:37:00 papa-legba dovecot: imap-login: Login: user=<mail_user>, method=PLAIN, rip=127.0.0.1, lip=127.0.0.1, mpid=26012, secured, session=<qxHST+eg7Nl/AAAB>
Mar 15 12:37:00 papa-legba dovecot: imap(mail_user): Logged out in=117 out=1502
即使mail_user我在squirrelmail/config/conf.pl域中设置的与帐户关联的电子邮件应该是什么，我也有点困惑papa-legba.ddns.net。我确实打开了 smtp 端口。