With the Antispam plugin from Dovecot, new spam mails can be pushed by hand into their own IMAP folder. Mails that are moved to this folder, spamassassin learns as spam mails. If a mail is moved from this folder (for example to the INBOX because it is not spam), spamassassin […]
After the DMARC Records checks in DMARC check on Debian Wheezy, I show how reports can be created and sent. First, we need a mysql database and a user to save the DMARC checks. Invoke mysql and run: CREATE DATABASE opendmarc; CREATE USER ‘opendmarc’@’127.0.0.1’ IDENTFIED BY ‘top_secret’; GRANT ALL PRIVILEGES […]
I use SPF records for many years. My implementation of SPF records in ISPConfig occurred to me to point out the advantages again. SPF is an authentication method that is stored in the DNS. This entry specifies which server can send mail for a particular domain. And why do I […]
I use on my servers ISPConfig, for IMAP and POP3 Dovecot is used. With Dovecot 2.x, the mails can also keep in sync between two servers. The replication is done via the Dovecot index files. So neither an error in the file system nor an accidentally deleted Maildir have a […]
With postfix and cron delivery of new mail messages may be certain times quite easily prevented. It can for example be prevent from that emails are delivered via push to inopportune times to a user. Add a hash-table in /etc/postfix/main.cf to smtpd_recipient_restrictions: check_recipient_access hash:/etc/postfix/hold In the file /etc/postfix/hold all domains […]
To prevent faked sender-adresses i recommend to use Sender Policy Framework (see www.openspf.org/Introduction). You can easily add the SPF-Modul from openspf.org to postfix. You need these three perl-modules Mail::SPF Net::DNS::Resolver::Programmable NetAddr::IP After installing the requied modules, get the SPF-modul from here. Extract the archiv and copy postfix-policyd-spf-perl to /usr/lib/postfix kopiert. […]
I use postscreen postscreen to prevent spam mails. Potential spam messages are rejected directly before they reach the server and the content must be scanned. You shouldn´t use postscreen if a Mail-User-Agents (MUAs) should be able to connect. Usually the TCP-Port 25 is only used for Mail-Transfer-Agents (MTAa) since MUAs […]