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ISP port blocking practice

Subject: ISP port blocking practice
From: johnl at iecc.com (John R. Levine)
Date: 4 Sep 2010 00:19:47 +0200
In-reply-to: <[email protected]>
References: <[email protected]> <[email protected]>

>> It's been extremely effective in blocking spam sent by spambots on
>> large ISPs.  It's not a magic anti-spam bullet.  (If you know one,
>> please let us know.)
>>
> That simply hasn't been my experience. I still get lots of spam from booted hosts in large provider networks, and yes, that includes many that block 25. As near as I can tell, 25 blocking is not affecting spammers at all, just legitimate users.

I know people at large ISPs with actual data.  Port 25 blocking is quite 
effective.

R's,
John

Follow-Ups:
- ISP port blocking practice
  - From: pstewart at nexicomgroup.net (Paul Stewart)
- ISP port blocking practice
  - From: dougb at dougbarton.us (Doug Barton)
- ISP port blocking practice
  - From: owen at delong.com (Owen DeLong)

References:
- ISP port blocking practice
  - From: johnl at iecc.com (John Levine)
- ISP port blocking practice
  - From: owen at delong.com (Owen DeLong)

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