MS Outlook with POP3 account randomly reasks authentication

Using MS Outlook with POP3 account from Interworx server often and randomly pops up Outlook authentication window - very annoying behaviour for customers. We have seen other people reports on that and we have been confirmed by Interworx that such problem exists and is caused by mail server software - one month is passed from reporting the issue yet we have not seen any fix for that issue. If anybody has any information about the issue - please share - I presume the issue is related to qmail/vpopmail and Outlook - not really interworx specific code.

What is the POP3 Memory limit you have set on the MDA Configuration page of Nodeworx?

We saw forum posts suggesting increasing memory limit per pop3 process - so we did and increased pop3 process memory to 524288000 - but this changed nothing. Also restarted processes after changing the setting.

Interesting, I have seen this happen as well, every once in a while.

For those of you seeing this problem on CentOS 5.2, 64 bit ONLY, please try the following, as root:

# wget
# cp /var/vpopmail/bin/vchkpw /var/vpopmail/bin/vchkpw.backup
# cp vchkpw /var/vpopmail/bin/vchkpw

Please provide feedback if that fixes the issue for you, or not.