• systemd management using systemctl and journalctl to check systemd logs

    systemd is like the service manager for your Centos and other modern Linux distributions (including Debian/Mint/Ubuntu) allows you to enable services, stop them, restart them, check their status and even reboot your system. The key commands or arguments you will use with systemctl are the following: Unit Commands: list-units [PATTERN...] List loaded units &nbs........
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  • Sendmail Gmail.com blocking

    relay=alt4.gmail-smtp-in.l.google.com. [], dsn=4.0.0, stat=Deferred: 421-4.7.0 [ 10] Our system has detected an unusual rate of This is strange because the mail server IP is not blacklisted anywhere and the IP itself has not been used for years and this server is clean and has only sent a few e-mails to gmail.com in its entire time. I wonder if this is a legacy block on a whole range of IPs as punishment for others in the block........
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  • stat=Deferred: 451-Non-existent domain mailserver.com

    Jul 11 15:20:58 tor sendmail[9617]: r6AKjOD07: to= mailserver.com was the hostname of the server, sendmail sends this by default and many mailservers will reject mail to a hostname that does not resolve or exist. The easiest way is just to change the hostname and make sure it does resolve to something. I read there is a way in sendmail.mc to manually set a hostname but I never got it working: vi /etc/mail/sendmail.mc define(`confDOMAIN........
  • How to log all PHP based E-mails for abuse

    Step #1 - Create Wrapper Script vi /usr/local/bin/phpsendmail #!/usr/bin/php ........
  • Enable SPAMASSASSIN on Postfix in 5 minutes

    Centos 5 Postfix and SPAMASSASSIN Tutorial yum install spamassassin chkconfig spamassassin on vi /etc/mail/spamassassin/local.cf ############## #required_hits 5 #report_safe 0 #rewrite_header Subject [SPAM] #5 is the least restrictive (means only the most obvious SPAM is caught. 0 is obviously the most restrictive/sensitive and would have lots of false positives require........
  • Understanding /etc/aliases from sendmail when using with postfix or other MTA's

    understanding /etc/aliases *remember to apply changes you need to run "newaliases" after editing /etc/aliases one thing I don't get is that it doesn't allow you to specify the whole e-mail address on the left-hand side eg: yourfullemail@domain.com: someotheremail@domain.com postalias: warning: /etc/aliases, line 109: name must be local (if you try the above) It works more like this: your........
  • Linux Centos/RHEL can't find php/apache/httpd/mysql/ftp/exim/sendmail ?

    I wasted a lot of time wondering why I could never find those packages. Check the /etc/yum.conf file and at the bottom look for the "exclude=" line. Below is what I found in mine exclude=apache* httpd* mod_* mysql* MySQL* da_* *ftp* exim* sendmail* php* bind-chroot* Just remove those entries or uncomment that line and you'll get access to the missing applications.........
  • PHP cannot access /usr/bin/openssl

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