Ian Eiloart wrote: >>>> The "headers_remove = User-Agent" line is something entirely different >>>> that tends to help. You'll find many references on the web to hotmail >>>> blocking certain messages that contain Thunderbird in the User-Agent >>>> header, but allowing through messages that are exactly the same, but >>>> without the User-Agent header. I tested this myself a while back and it >>>> was true. >>> Why would an MUA add a "User-Agent" header? It's an HTTP or net-news >>> header, not a mail header. >>> <http://www.iana.org/assignments/message-headers/perm-headers.html> >>> Arguably, Microsoft are doing the right thing by punishing clients for >>> using non-standard headers. >> Non-standard headers? You can add *any* arbitrarily named header you >> want to an email. At least Thunderbird and Mutt both use "User-Agent". >> I've not tested other MUAs. Microsoft aren't, "doing the right thing," >> or anything even close to sensible by scoring so harshly on this header. > > RFC2822 does say that you can add other headers, but not arbitrarily named > - the name can't clash with a registered name.
I can't find where it says that... It does list a bunch of headers that are to be used to store a certain type of information such as "Subject, From, To" etc, and I can see why you wouldn't use those headers for storing arbitrary data. Eg: "From: Thunderbird Client" would be bad. But I don't see anywhere where it says I can't use "User-Agent: Whatever I want" in email headers. > However, that doesn't mean > that every imaginable header is "Standard". Indeed rfc2076 lists several > headers as "not internet standard". I'd suggest that a "standard" header is > one that's registered with IANA according to rfc3864: > <http://tools.ietf.org/html/rfc3864>. I guess, for clarity, I should have > used the phrase "registered". Hmmm. Can you quote a relevant passage from a relevant RFC that says or even mildly suggests that you "MUST NOT" or even "SHOULD NOT" use this header for this purpose? > I suspect that Microsoft are adding spam points to messages with > non-standard headers, which would explain why some messages are acceptable > when they don't contain a user-agent header. Email systems add all sorts of unusual headers to emails. I'd suggest that it's less likely for a spam to contain a "non-standard" header than a ham, not the other way round. Mike -- ## List details at http://lists.exim.org/mailman/listinfo/exim-users ## Exim details at http://www.exim.org/ ## Please use the Wiki with this list - http://wiki.exim.org/