atom feed13 messages in net.sourceforge.lists.courier-usersRe: [courier-users] Considerable time...
FromSent OnAttachments
Sándor ZsoltMay 26, 2006 2:25 am 
Daniel FaberMay 26, 2006 3:32 am 
Sam VarshavchikMay 26, 2006 3:50 am 
Sándor ZsoltMay 26, 2006 5:36 am 
Gordon MessmerMay 26, 2006 9:52 am 
Daniel FaberMay 26, 2006 10:33 am 
Gordon MessmerMay 26, 2006 10:40 am 
ArnoMay 26, 2006 11:26 am 
Daniel FaberMay 26, 2006 12:10 pm 
Sándor ZsoltMay 29, 2006 2:51 am 
Sam VarshavchikMay 29, 2006 6:16 am 
Sándor ZsoltMay 30, 2006 12:26 am 
Sam VarshavchikMay 30, 2006 3:55 am 
Subject:Re: [courier-users] Considerable time when "550 unknown user" error msg. at local domain
From:Daniel Faber (ma@daniel-faber.de)
Date:May 26, 2006 3:32:58 am
List:net.sourceforge.lists.courier-users

On 26/05/06 11:25, Sándor Zsolt wrote:

The whole system works fine, but recently notified that the incoming mails - from the Internet - suffer considerable delay. Tracking the problem we found out that it is caused by the huge amount of spam mails, where the local domain is correct, but the addressee is wrong so courier gives back an:

550 User unknown

error message. This is all right, the only problem is that this response arrives after a considerable time. It takes at least 8 secs, but sometimes even 2 mins.

2 minutes and 8 seconds?

Look at this SMTP dialog:

$ telnet helium.leptonite.de smtp Trying 85.214.27.32... Connected to helium.leptonite.de. Escape character is '^]'. 220 helium.leptonite.de ESMTP HELO its.me 250 helium.leptonite.de Ok. MAIL FROM: <ma@daniel-faber.de> 250 Ok. RCPT TO: <noth@leptonite.de> --- delay: 8 seconds --- 550 User unknown. RCPT TO: <noth@leptonite.de> --- delay: 16 seconds --- 550 User unknown. RCPT TO: <noth@leptonite.de> --- delay: 32 seconds --- 550 User unknown. RCPT TO: <noth@leptonite.de> --- delay: 64 seconds --- 550 User unknown. RCPT TO: <noth@leptonite.de> --- delay: 128 seconds --- 550 User unknown.

My guess: it's not a bug, it's a feature to slow down spammers.

Daniel