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Thread: SPAM! - TMDA or other Challenge Response with Zimbra?

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    bjquinn is offline Advanced Member
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    Default SPAM! - TMDA or other Challenge Response with Zimbra?

    I've asked this question before, but never really got anywhere -- I'd like to set up TMDA or some other Challenge-Response system with Zimbra. Setting up TMDA ought to be easy, since it was designed for Postfix, but I hit some barriers with respect to how Zimbra sets up its mail storage directories. I can't seem to find much out there on the internet, so I was wondering if anyone had ventured into setting this up before or had any ideas.

    Oh, and before I start getting flamed for bringing up Challenge Response...

    I've tried Spamassassin, all the "extra" anti-spam stuff in the wiki, including greylisting. I have superiors who simply demand the added spam protection that a well-designed CR system (like TMDA) can achieve and that they had been spoiled with in the past. I (and the users) understand the downsides of CR (both for the user and the collateral damage), but the people who make the decisions don't care and insist on CR and its effectively 100% spam protection (even though some would argue it's closer to 110%, which admittedly isn't really a good thing).

    Lastly, for what it's worth, I had only barely appeased these picky users for several months with SA and the extra customizations on the wiki, but lately a flurry of pornographic spam has snuck its way in, and marking them all as junk doesn't seem to help much. SA is running and still catching the vast majority of the spam that comes in, but now every day each user receives half a dozen blatantly XXX rated spam (it's not even trying to obfuscate the "nasty" words and it's still getting through!), and they won't put up with it any longer. I'm running 4.5.8, but if the suggestion is to upgrade, I can't possibly be expected to go through the upgrade process every couple of months to keep ahead of the spam curve!

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    uxbod's Avatar
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    perhaps take a look at FuzzyOcrPlugin - Spamassassin Wiki I appreciate it is not CR but will help in the battle.

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    uxbod's Avatar
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    just read up on TMDA and it appears to be straightforward to implement. What issues were you having with it with respect to Zimbra ?

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    bjquinn is offline Advanced Member
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    No specific problems, really, I'd just never seen anyone implement it on Zimbra. Have you actually tried it? Does it work on Zimbra as straightforwardly as the TMDA documentation for postfix suggests? Also, what about the tmda-ofmipd thing that allows auto-whitelisting of outgoing messages? How would you make that work, especially with the web client?

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    uxbod's Avatar
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    Yes it can be made to work, but all the docs I have read says stay well away. It can cause more harm than good, and end up getting your MTA blocked!

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    bjquinn is offline Advanced Member
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    I'm more than well aware of the "risks", but I've administered multiple TMDA servers for several years now, and the benefits far outweigh the downsides. I just don't know how to make it work with Zimbra.

    It's a completely different kind of email experience when you know you'll get less spam a year than you can count on one hand, and you're not continually having to monkey around with SA rulesets and upgrading your version of Zimbra to try to keep up with the spammers, like I've had to do recently when we got bombarded by a bunch of backscatter spam. TMDA would have blocked it and I wouldn't have even known it was happening.

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