Firefox+Horde webmail+PDF attachment=invalid mime type
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Leonardo Boiko
Aug 2, 2016, 2:30:10 PM8/2/16
to rspamd
Hi,
I don't think this is a problem with rspamd, but I just wanted to get it online somewhere.
We had users complaining that their emails were being tagged as spam. After investigation, it turns out the Horde IMP webmail takes the mime-type for attachments from the browsers. Out of 3 Firefoxes we tested, one uploaded PDFs as application/pdf; one as application/x-download; and one as x-unknown/unknown . The latter two trip MIME_BAD_ATTACHMENT. This, plus FORGED_RECIPIENTS_MAILLIST failing to activate (looking into this now), were enough to spam them.
I'm not sure what to do about this, so we overrode the rule's weight.
I don't think this is a problem with rspamd, but I just wanted to get it online somewhere.
We had users complaining that their emails were being tagged as spam. After investigation, it turns out the Horde IMP webmail takes the mime-type for attachments from the browsers. Out of 3 Firefoxes we tested, one uploaded PDFs as application/pdf; one as application/x-download; and one as x-unknown/unknown . The latter two trip MIME_BAD_ATTACHMENT. This, plus FORGED_RECIPIENTS_MAILLIST failing to activate (looking into this now), were enough to spam them.
I'm not sure what to do about this, so we overrode the rule's weight.
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