EMail Servers related tutorial/FAQ

How to configure Postfix relayhost (smarthost) to send eMail using an external smptd

in Debian / Ubuntu, EMail Servers, Linux last updated August 22, 2016

How do I configure Postfix MTA to send eMail using an external cloud-based SMTP server (with username: password) from a web server on Linux or Unix-like system? How do I configure an Ubuntu server and postfix as the relay server (smarthost)?

Start / Stop / Restart Postfix Mail Server

in EMail Servers last updated June 23, 2011

How do I start / stop / restart my postfix mail server under Linux or UNIX operating systems?

Linux Configure Sendmail as SMTP Mail Client ( submission MTA )

in CentOS, Debian / Ubuntu, EMail Servers, Fedora Linux, Linux, Networking, RedHat and Friends, Sendmail, Suse, Ubuntu Linux, UNIX last updated July 24, 2009

I‘ve central e-mail server. Other servers does not need to operate as a mail server. How do I configure Sendmail as submission-only e-mail server (mail client) under CentOS / Fedora / RHEL / Debian Linux / UNIX like operating systems?

Postfix Forward Email To Another Email Account

in CentOS, Debian / Ubuntu, EMail Servers, Fedora Linux, FreeBSD, Linux, OpenBSD, Troubleshooting, UNIX last updated July 1, 2009

I‘ve multiple virtual domain hosted on CentOS Postfix server. How do I forward selected virtual domain email to yahoo / gmail or other email account using Postfix email server?

Postfix Hide Client (MUA) System IP Address / Hostname

in CentOS, Debian / Ubuntu, EMail Servers, Fedora Linux, FreeBSD, Networking, RedHat and Friends, Suse, Troubleshooting, UNIX last updated June 17, 2009

I‘ve central mail server gateway. All of our internal systems through this box. How do I remove or hide the hostnames and IP addresses of our internal systems from the messages headers before they go out to other users for security purpose?

SPAMHAUS BLOCKLIST ADDRESS IS WRONG MUST FIX Error and Solution

in EMail Servers, Linux, Networking, RedHat and Friends, Troubleshooting, UNIX last updated May 7, 2009

I‘ve configured RBL for my postfix based mail server and I’m getting an error that read as follows:

May 3 04:35:37 mx02 postfix/smtpd[10956]: NOQUEUE: reject: RCPT from ant251.neoplus.adsl.tpnet.pl[83.26.101.251]: 554 5.7.1 Service unavailable; Client host [83.26.101.251] blocked using xen.spamhaus.org; SPAMHAUS BLOCKLIST ADDRESS IS WRONG MUST FIX; from= to= proto=ESMTP helo=

How do I fix this problem?

Postfix mail for domain.com loops back to myself Error and Solution

in CentOS, Debian / Ubuntu, EMail Servers, Fedora Linux, FreeBSD, Linux, OpenBSD, RedHat and Friends, Troubleshooting last updated June 2, 2009

I can send and receive mail using user@example.com, but system generated emails such as root@mail.example.com bounce backup with an error:

May 1 03:14:52 mail postfix/smtp[62798]: 23CA4BD6B40: to=, relay=none, delay=0.01, delays=0/0/0/0, dsn=5.4.6, status=bounced (mail for mail.example.com loops back to myself)

How do I fix this error?

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