Step one. Which DSPAM is right for you? The DSPAM project makes dspam part of the LDA (Local Delivery Agent). Pydspam puts dspam into the MTA (Mail Transfer Agent - sendmail with pymilter). The advantage of doing dspam in the LDA is that any aliasing has already been resolved. You need only configure mailboxes. The advantage of doing dspam in the MTA is it can screen an entire company as a gateway with multiple domains. Unfortunately, this means you have to tell it about all the aliases that comprise each account. (Also, pydspam is still uses dspam- - the Dspam API has changed for newer versions.) If the LDA is right for you, you'll want to use the official Dspam package. If the MTA approach is what you want, then pydspam is what you want. In either case, you will still want pymilter to block forgeries, Windows executables, etc. So, lets assume you want to install pymilter, and may or may not wish to install pydspam. Step two. Obtaining RPMS. For basic pymilter you'll need: python-2.4 milter-0.8.2 (the RH9 rpm should work on Fedora Core - let me know) sendmail-8.13.x (with milter support enabled) and for SPF you'll need: pydns-2.3.0-2.4 and for SRS you'll need: pysrs-0.30.9-1.py24 I'm pretty sure you will want to have SPF and SRS available. Step three. Activate basic milter. Activate the basic milter by editing /etc/mail/ and adding: INPUT_MAIL_FILTER(`pythonfilter', `S=local:/var/run/milter/pythonsock, F=T, T=C:5m;S:20s;R:5m;E:5m') You can then "make" and restart sendmail. Tail /var/log/milter/milter.log while SMTP clients connect to your sendmail instance. This should show you what the milter is doing. By default, milter-0.8.2 rejects on SPF fail, except for listed domains (that are known to be broken). Some admins don't like that, and 0.8.3 will use the /etc/mail/access database to configure SPF responses. For now, if you don't like SPF, you can disable spf by replacing "import spf" with "spf = None" around line 285 in /var/log/milter/ Step four. Tweaking the basic config. Most pymilter configuration is in /etc/mail/pymilter.cfg. By default, milter scans attachments for executable extensions. You can turn this off by setting banned_exts to the empty list. There are options to scan ZIP attachments and rfc822 attachments. When it finds a banned file type, milter saves the original message in /var/log/milter/save, and replaces the attachment with a plain text warning message. Configure hello_blacklist with your own helo name and domains - which you know cannot legitimately be used by external MTAs. Configure trusted_relay with your secondary MX servers, if any. These should also run pymilter with similar policies. (But this isn't needed for initial testing.) Configure internal_connect with subnets of your internal SMTP clients. Internal connections skip SPF testing and other policies. Configure internal_domains with domains used by your internal SMTP clients. If they attempt to use any other domain, the attempt is blocked and the client is logged as a "zombie". Conversely, any attempt by an external MTA to use one of your internal domains is treated as a forgery and blocked (a simplified form of local SPF). Adjust porn_words and spam_words - these block emails with a Subject containing the listed strings. They can be empty to disable Subject string blocking. Advanced SPF configuration. The sendmail access file, or another readonly database with that format, can be used for detail spf policy. SPF access policy record are tagged with "SPF-{Result}:". Results are Pass, Neutral, Softfail, Fail, PermError. Currently supported policy keywords are OK, CBV, REJECT. Currently, TempError always results in TEMPFAIL. The default policies are set in pymilter.cfg. The defaults if none of the config options are set are as follows: SPF-Fail: REJECT SPF-Softfail: CBV SPF-Neutral: OK SPF-PermError: REJECT SPF-Pass: OK The tag may be followed by a specific domain. For instance, to require a Pass from REJECT REJECT The CBV policy requires a valid HELO name. If the EHLO name is RFC2822 compliant, then a DSN is sent to the alleged sender. The template for the DSN is selected according to the SPF result: Fail: softfail.txt SoftFail: softfail.txt Neutral: neutral.txt PermError: permerror.txt None: strike3.txt An SPF-Pass is always accepted by the milter. Domains can be blacklisted via sendmail in the access file or via a RHS DNS blacklist. To be continued. Forthcoming topics: SRS config pydspam config wiretap config