From 89b7b67a13ebb7965cc7f13ad0595e2194a2d34c Mon Sep 17 00:00:00 2001 From: Jannis Hoffmann Date: Wed, 3 Jul 2024 15:48:04 +0200 Subject: add sqmail-4.2.29a --- doc/BLURB | 251 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 251 insertions(+) create mode 100644 doc/BLURB (limited to 'doc/BLURB') diff --git a/doc/BLURB b/doc/BLURB new file mode 100644 index 0000000..ba7ad5a --- /dev/null +++ b/doc/BLURB @@ -0,0 +1,251 @@ +s/qmail BLURB +============= + +s/sqmail inherits all features of qmail, since it includes its +concept and its code. + +Confidentially: s/qmail adds transmission confidentially by means +of TLS encryption. TLS encryption is provdided by for all protocols +except for QMTP while requiring UCSPI-SSL. + +Privacy: s/qmail does currently not provide email privacy. +The persistance storage (Queue) is unencrypted and shared. +This might be changed in forthcoming releases. + +Authentication: s/sqmail supports user authentication for sending +and receiving mails by means of SMTP(S). QMTP and QMQP however, are +solely host-to-host mail transfer protocols. + +Distribution: s/qmail uses the concept of distributed queues to be +fed either by SMTP or QMTP/QMQP. + +Multi-domain capability: s/qmails allows to set up differently +parametrized transport/distribution pathes based on the domains +under control of the MTA. This concept is close to a multi-tenant +behavior; regarding the domain, not the individual recipient/sender. + + +Authenticated Email Senders +=========================== + +Within s/qmail both + +* qmail-smtpd for receiving emails and +* qmail-remote for sending emails + +support authentication regarding the methods + +- PLAIN, +- LOGIN, and +- CRAM-MD5. + +Additionally, + +* qmail-smtpd accepts authentication based on + +- X.509 client certs. + +* qmail-popup together with +* qmail-pop3d + +provide authentication by means of the methods + +- USER and +- APOP. + +The authentication module + +* qmail-authuser + +replaces the old + +* checkpassword and perhaps +* cmd5checkpw + +programs with much more flexibility. +Given a LDAP infrastucture, + +* qmail-ldapam + +can be used to call the user data from here. + + +Validation receiving Mails +========================== + +Within s/sqmail + +* qmail-smtpd, +* qmail-qmtpd, and +* qmail-qmqpd + +are able to receive email from the Internet. + +While + +* qmail-qmtpd and +* qmail-qmqpd + +use QMTP/QMQP transmitting emails and are currently +only supported by Postfix, Qmail, and s/qmail in a +dedicated environment, + +* qmail-smtpd + +supports both SMTP and ESMTP and is a potential +target for spam, virii, and other unsolicited email. + +Thus + +* qmail-smtpd + +supports greylisting and provides filters for the + +- SMTP envelope information, +- the email content (with different mechanisms) and in + particular to check/validate the existance of a potenial +- email recipient. + +For this purpose, the modules + +* qmail-smtpam, +* qmail-vmailuser, +* ldapam, and +* qmail-authuser together with +* qmail-ldapam + +are available. The RECIPIENTS mechanism supports a +domain dependent validation based on a PAM mechanism +or perhaps a cdb. + +Domain based SPF lookups are provided for + +* qmail-smtpd. + + +Anti-Spam Mechanisms +==================== + +* rblsmtpd (out of the package ucspi-tcp6) + +supports + +- Relay Black Lists (RBL) and +- Greetdelay + +prior of receiving mail by + +* qmail-smtpd. + +In adddition, + +* qmail-smtpd + +provides by means of the + +- QMAILQUEUE hook + +an interface to SpamAssassin and other tools. +A wrapper script is included. + +Further, the well known + +- postgrey + +server can be used by + +* qmail-postgrey + +as an add-on to be called by + +* qmail-smtpd. + + +Anti-Virus Mechanism +==================== + +* qmail-smtpd + +uses + +- MIME and +- LOADER type + +filters to allow an on-the-fly recognition of executable. + +Anti-Virus tools are supported either by + +- QHPSI or by the +- QMAILQUEUE hook. + +A (combined) wrapper script for + +* qmail-queue + +is provided. + + +Bounce Control +============== + +Within s/qmail + +* qmail-send + +is responsible to generated bounces, ie. None Deliverable Reports (NDR). +s/qmail uses qmail's concept to generate the NDRs in the QSMBF (qmail-send +Message Bounce Format) unaltered (http://cr.yp.to/proto/qsbmf.txt). + +To control NDR, s/qmail provides two means: + +* qmail-send + +can be adviced -- while generating a NDR -- to limit it to N bytes. +Effectively this means the orgininal message is truncated and not +completely bounced. + +Upon transmitting bounce messages to third-party MTAs + +* qmail-remote + +can be set-up to use a particular + +- bounce queue (s/qmail instance) + +to take care of this delivery. Thus generic message transmission +is decoupled from bounce processing and does not inflict with it. + + +Logging, Monitoring, and Housekeeping +===================================== + +s/qmail writes log information for + +- qmail-send (qmail-local & qmail-remote/qmail-smtpam) on FD 2 +- qmail-popup (authentication information only) on FD 5 +- qmail-smtpd (see 'LOGGING') on FD 2 + +Either the log information is fed by means of 'splogger' +into the Syslog, or treated by daemontool's 'multilog' +which automatically does the housekeeping and provides +a TAI64N timestamp for each line (event). + +Using 'multilog', the log information can be +picked up by 'qmail-mrtg' and graphically +displayed using 'MRTG' or 'RRDtool'. + +The log information can be analysed using +the 'qmailanalog' facility and for convenience +the program 'tai64nfrac' is included. + +The separate package 'newanalyse' provides +an easy customizable umbrella script for analysis +and long-haule housekeeping together with the +capability to track each incoming and outgoing +mail. + + +E. Hoffmann -- 2021/01/01. + + + -- cgit v1.2.3