I have found some clue.

When one of 6 users tried to receive his mails(40M), always failed to fetch the 5th mail. And then all tcp/ip connections reset for a while(about 5-10 minutes). if he delete his mail account from outlook. Then all things go well.

Which reasons may cause this phenomenon? Would you pls provide some clues about source design,especially the RST cases?

We setup the FC3 system on 2005/6/18, and copy the user XXX data from orignal FC1 system to FC3 /var/spool/mail/XXX. I noticed that his earliest mail unfetched is 2004/12/9. Is it possible that this is caused by possible data crash or data format dismatch?

And what can I do to resolve it?

From: "Yi Xuan" xuanyi365@hotmail.com To: dovecot@dovecot.org Subject: RE: [Dovecot] POP3 problem about multi users from one IPaddressconcurrent Date: Sun, 04 Sep 2005 09:48:53 +0000

Additional information

1.when I check the process by #ps -ef |grep dovecot

I found about 20 processes with earliest time 8/27 still alive. Does that matter?

2.PlaceA is 10M broadband, and PlaceB is 512k with about 30 users.

...

From: "Yi Xuan" xuanyi365@hotmail.com To: dovecot@dovecot.org Subject: [Dovecot] POP3 problem about multi users from one IP addressconcurrent Date: Sun, 04 Sep 2005 01:46:35 +0000

Hi,all

I have a POP3 problem about multi users from one IP address concurrent.

[Issue description] The network architecture is as following. I have setup a mail server(sendmail/dovecot) in PlaceA with IP_A. And about 6 users are receving mail from the same IP_B( NATed public IP) in PlaceB. Their mails are many( about 1Mb/hour each) and ususally set fetch time as 10min/fetch.

Then they complain that their mails often cannot be downloaded.

[Reason investigation] I noticed that 1.when one of them fail to fetch mail. All TCP IP connection between IP_A and IP_B will be RST.which means that http/ssh/pop/smtp all not work for a while. And after about 10 minute, the http/ssh can work well. 2.I have asked them to backup and delete pop accounts and use webmail through imap provided by dovecot.And that seems work well but inefficient.

I think this maybe because of multi users from one IP address concurrent,

[Question] Would you pls provide some suggestion or solution about this issue? Is this a bug of dovecot or just a mis-configuration I don`t know?

Thanks in advance for any advice.

Best regards, Yi Xuan