Re: Avoiding cool-off retry delay for some domains

2008-11-03 Thread Victor Duchovni
On Fri, Oct 31, 2008 at 07:42:59PM -0400, Vintinner, M. Scott wrote: When their servers are experiencing an outage , I see: Oct 28 09:24:41 mta1 postfix/smtp[24419]: connect to wec-imail1.bank.com[xxx.xxx.91.91]: Connection refused (port 25) Connection refused is not what you would expect

Re: Avoiding cool-off retry delay for some domains

2008-11-03 Thread Jay Chandler
On Nov 3, 2008, at 10:32 AM, Victor Duchovni wrote: smtp-finger: Connected to wec-imail1.wachovia.com[169.200.91.91]:25 smtp-finger: 220 wec-imail1.wachovia.com ESMTP Ready. smtp-finger: EHLO hqmtaint02.ms.com smtp-finger: 250-wec-imail1.wachovia.com Hello hqmtaint02.ms.com

Re: Avoiding cool-off retry delay for some domains

2008-11-03 Thread Victor Duchovni
On Mon, Nov 03, 2008 at 12:02:59PM -0800, Jay Chandler wrote: On Nov 3, 2008, at 10:32 AM, Victor Duchovni wrote: smtp-finger: Connected to wec-imail1.wachovia.com[169.200.91.91]:25 smtp-finger: 220 wec-imail1.wachovia.com ESMTP Ready. smtp-finger: EHLO hqmtaint02.ms.com smtp-finger:

Re: Avoiding cool-off retry delay for some domains

2008-11-03 Thread Terry Carmen
Vintinner, M. Scott wrote: One of our very important clients (a major bank), is having ongoing problems with denial-of-service style dictionary SPAM attacks. Their anti-spam/firewall teams are slow to respond to these outbreaks, so there may be periods of several hours where we will get

Re: Avoiding cool-off retry delay for some domains

2008-11-03 Thread Victor Duchovni
On Mon, Nov 03, 2008 at 04:33:47PM -0500, Terry Carmen wrote: Is there any chance you could get them to try installing something like fail2ban, which can block connections from IPs that are doing the dictionary attacks? Trying to fix postfix to handle a DOS attack would seem to be more

Re: Avoiding cool-off retry delay for some domains

2008-11-03 Thread Terry Carmen
Victor Duchovni wrote: Is there any chance you could get them to try installing something like fail2ban, which can block connections from IPs that are doing the dictionary attacks? Trying to fix postfix to handle a DOS attack would seem to be more difficult than preventing it in the first

Re: Avoiding cool-off retry delay for some domains

2008-11-03 Thread Victor Duchovni
On Mon, Nov 03, 2008 at 05:56:48PM -0500, Terry Carmen wrote: The destination system is not Postfix. The sending system is experiencing connection problems. We don't know anything about configured concurrency limits, volumes, ... the OP has provided only minimal information. Sorry, I was

Avoiding cool-off retry delay for some domains

2008-10-31 Thread Vintinner, M. Scott
One of our very important clients (a major bank), is having ongoing problems with denial-of-service style dictionary SPAM attacks. Their anti-spam/firewall teams are slow to respond to these outbreaks, so there may be periods of several hours where we will get frequent connection refused

Re: Avoiding cool-off retry delay for some domains

2008-10-31 Thread Terry Carmen
Vintinner, M. Scott wrote: One of our very important clients (a major bank), is having ongoing problems with denial-of-service style dictionary SPAM attacks. Their anti-spam/firewall teams are slow to respond to these outbreaks, so there may be periods of several hours where we will get

Re: Avoiding cool-off retry delay for some domains'

2008-10-31 Thread Wietse Venema
Vintinner, M. Scott: One of our very important clients (a major bank), is having ongoing problems with denial-of-service style dictionary SPAM attacks. Their anti-spam/firewall teams are slow to respond to these outbreaks, so there may be periods of several hours where we will get frequent

RE: Avoiding cool-off retry delay for some domains

2008-10-31 Thread Vintinner, M. Scott
about it. As I said, I'm pretty confident that the problem is on their end. -Scott -Original Message- From: Terry Carmen [mailto:[EMAIL PROTECTED] Sent: Friday, October 31, 2008 7:04 PM To: Vintinner, M. Scott Cc: postfix-users@postfix.org Subject: Re: Avoiding cool-off retry delay