Michael Thomas wrote: > On 08/17/2010 04:08 AM, Ian Eiloart wrote: >> Yes, out Exim/Spamassassin installation does DKIM (but not > ADSP) evaluation during the SMTP session. > > I'm not positive, but I believe that Ironport does it that > way too. > > Is there anybody who *doesn't* do DNS lookups at SMTP time these > days? That's all DKIM really amounts to, and the entire mail > infrastructure would seize if we weren't (cf, blacklists).
In the past, I followed how implementations of SPF was being done - at SMTP or post acceptance. I recall it was interestingly spread out depending on the software being used. Most of the MTAs that allowed embedded hooking with programming scripts had scripts available and others used general 2822 text file mail bot SPF scripts. But I've also followed other MTAs such as YAHOO, AOL, MSN.COM, gmail.com and so on, where you definitely saw a shift towards DATA level rejections than in the past. The only issue overall between the two was how the ENVELOPE information was read or written into the 2822 file for post smtp to read. In general, you could get this from the top Received: line stamped by the MTA (a requirement), but other MTA add specific syntax envelope info at the top before the 2822 blocks. At the SMTP level, you don't need to work about that but generally, the scripting language is proprietary to the MTA engine in use. So POST SMTP scripts tend to be more general and made to work with for most MTAs, with no or little change. -- Hector Santos, CTO http://www.santronics.com http://santronics.blogspot.com _______________________________________________ NOTE WELL: This list operates according to http://mipassoc.org/dkim/ietf-list-rules.html
