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 […]
To send emails with Postfix, a few things have to be considered. These are either defined in RFCs or generally useful. 1. matching reverse DNS RFC1912 requires that the PTR record and the A record in DNS match. On the one hand it shows that the administrator understands the RFCs, […]
Perfect Forward Secrecy (PFS) is a data encoding property that ensures the integrity of a session key in the event that a long-term key is compromised. PFS accomplishes this by enforcing the derivation of a new key for each and every session. Setup Dovecot Dovecot (at least from 2.1.x) already […]
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 […]
If you see host aspmx.l.google.com[2607:f8b0:400d:c02::1b] said: 550-5.7.1 [2607:5300:101::79e] Our system has detected that this message does 550-5.7.1 not meet IPv6 sending guidelines regarding PTR records and 550-5.7.1 authentication. Please review 550-5.7.1 https://support.google.com/mail/?p=i…tication_error for more 550 5.7.1 information. h1si3408978qew.71 – gsmtp (in reply to end of DATA command) the destination dropped […]