Now blogging at diego's weblog. See you over there!

mail's back

Okay, so, I admit, I wasn't ready to ditch email yet. This morning, the reasons remained: if I loaded my mail server I suddenly received a flood of messages, including the virus, spam, and "rejected" messages from addresses that had received the virus with my own address spoofed.

But even as the problems remained, I needed email, not least to reply to the clevercactus-dev list, and even do some work. Last week's crisis led me to think in new directions, and maybe we'll be able to come up with a good solution for this problem (or part of it). In the meantime, I had to get my mail back. I had no choice.

So I breathed deeply and started looking for configuration options for postfix, the mail server that I use. I found good information here, here and especially here. I started adding options and it took me some time to get them running, in particular the regular expressions that parse both the headers and the body of the message were a bit of a pain to get right, as usual. (I am now, for example, rejecting EXE, PIF, BAT and other MS-virus-related attachments, knowledge of MIME and how it is usually done has its uses :)).

I still have to tweak things a bit, but in principle it should be back to normal. Interestingly enough, most of the messages are being rejected with the error "Helo command rejected: need fully-qualified hostname". I wonder if this will affect legitimate email (I am not entirely sure which of the postfix settings is requiring this, maybe it's "reject_non_fqdn_sender" or "reject_non_fqdn_recipient" or "reject_unknown_client"...).

If you're trying to contact me via email and you can't, leave a comment here--also, if I haven't replied in the last few days just give me a few hours as I go through my queue.

Update: in the roughly three hours since I completed the filtering configuration, postfix has rejected 1128 emails, most of them infected with the Sobig virus. One thousand one hundred twenty-eight! Jeez. Anyway, it feels weird now. Like the quiet right after the storm has passed.

(In the time it took to write the previous paragraph, another nine invalid emails were bounced!)

Categories: technology
Posted by diego on August 25 2003 at 10:20 AM

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