Comments on: High Risk Extensions

By: Jeremy C. Wright

Jeremy C. Wright — Fri, 17 Sep 2004 18:50:19 +0000

It doesnt’ reduce the bandwidth, it reduces the load on the mailservers. Zips get blocked at the SMTP level by our anti-spam server. It also means none of it gets stored on the disk arrays of the mail servers either, which is actually 1GB in monthly savings in terms of disk space.

By: Andy

Andy — Fri, 17 Sep 2004 18:39:36 +0000

not sure how blocking zips reduces your bandwidth – surely you have to retrieve/accept the email before you know theres a zip in it? By which point the bandwidth has been used up. A virus scanner would pick up and delete the virus so your bandwidth to the user isn’t going to be affected (much) apart from the email which says “click here to view my naughty web pages” with an attachment that says “this file was deleted as it contained a virus”. Surely this slight overhead is worth not having the hassles of users being unable to send anything to you because you’ve blocked zip and all office docs!

Having said that, I zipped up a 53mb file to 700k and sent it. The receiver rejected it because the *unzipped* file was too big!

By: Shaun

Shaun — Fri, 17 Sep 2004 18:21:50 +0000

We block zips at work too. It’s a major PITA to be honest, but it does cut down on the risk/traffic factor significantly. And you can always rename them to .foo

By: Jeremy C. Wright

Jeremy C. Wright — Fri, 17 Sep 2004 15:58:22 +0000

We still block zips. We don’t context scan them though, so users are free to rename them.

It’s definitely an inconvenience, but we haven’t had any actual complaints since the system notifies users of the issue, of the workaround and who to call if they have problems.

The issue was with viruses sending millions of zips. That traffic has stopped now, and there is no load being placed on the mail servers (specifically storage) as a result.

By: VodkaFish

VodkaFish — Fri, 17 Sep 2004 15:48:27 +0000

Did you wind up unblocking .zip or are you just having your users deal with it? So much is zipped up already to avoid being blocked (any sort of MS Office document comes to mind) that I don’t think my company could ever do such a thing.

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