PSCS Wiki

Training the VPOP3 Spam Filter

Anonymous (anonymous@undisclosed.example.com) — 2018-11-14T10:45:49+00:00

Training the VPOP3 Spam Filter The VPOP3 spam filter has a couple of mechanisms which can be used to 'train' it to distinguish between spam and not-spam. Bayesian Filter The Bayesian filter this looks at words in messages sent and received and their probabilities of being contained in spam and not-spam, and works out an overall probability of the message being spam or not-spam based on the combination of those probabilities.

Backscatter

Anonymous (anonymous@undisclosed.example.com) — 2018-11-14T10:45:49+00:00

Backscatter In email, “backscatter” is the term used if you send bounce messages back to spam messages. As most spam messages use forged email addresses, then the bounce messages will go to an innocent person, who will find them very annoying. Stopping VPOP3 from sending Backscatter

-ERR Unknown User

Anonymous (anonymous@undisclosed.example.com) — 2018-11-14T10:45:49+00:00

-ERR Unknown User -ERR Unknown User is a POP3 error. There are two places you can receive it: * If you receive it as part of a 'POP3 Client Error' email message from VPOP3, then it means that VPOP3 was unable to log on to your ISP's mail server because the ISP POP3 server reported an error

Error Message Handling

Anonymous (anonymous@undisclosed.example.com) — 2018-11-14T10:45:49+00:00

Error Message Handling VPOP3 will normally send an error message to the Main Administrator every time it encounters an error. We recommend you leave it like this in most cases - if an error message occurs repeatedly, then it usually means there's an underlying problem which needs resolving rather than ignoring.

Exchange 2007

Anonymous (anonymous@undisclosed.example.com) — 2018-11-14T10:45:49+00:00

Exchange 2007 You can link VPOP3 to Exchange Server, so that Exchange Server sends outgoing mail through VPOP3 and VPOP3 sends any incoming mail directly to Exchange Server. You should first of all set up VPOP3 to send and receive Internet email as normal.

How to Forward Messages to an External Address

Anonymous (anonymous@undisclosed.example.com) — 2025-08-18T15:13:06+00:00

How to Forward Messages to an External Address There are two possible methods to forward messages to an external address: * Use this method if it is for a person who might want to receive their email whilst in the office and/or get the mail sent to an external address.

Transmission Receipt Message

Anonymous (anonymous@undisclosed.example.com) — 2018-11-14T10:45:49+00:00

Transmission Receipt Message This is not an error message, but we are listing it here because it confuses some people. VPOP3 sends a 'Transmission Receipt' when a message is sent out, and it contains a header asking for the receipt. The default configuration is that it will send the transmission receipt if the sender asks for a read receipt.

421 4.3.2 VPOP3 SMTP Server access disabled - content scanner problem!

Anonymous (anonymous@undisclosed.example.com) — 2018-11-14T10:45:49+00:00

421 4.3.2 VPOP3 SMTP Server access disabled - content scanner problem! This usually happens if the “VPOP3 AV” virus scanner has a problem it can't automatically recover from. This may be a fatal error, or a licencing issue. You can check this on the Settings

Attachments have been removed or renamed

Anonymous (anonymous@undisclosed.example.com) — 2018-11-14T10:45:49+00:00

Attachments have been removed or renamed If you have received an email and one or more of its attachments have been removed or renamed, it might be a result of Attachment Filtering. You can inspect the filtering rules by going to Administration Settings -> Settings ->

Configuring Calendar on iOS

Anonymous (anonymous@undisclosed.example.com) — 2018-11-14T10:45:49+00:00

Configuring Calendar on iOS These instructions are for configuring a new Calendar account on iOS for iPhone, iPad and iPod Touch. The version of iOS used for these instructions is iOS v6.0, but they will probably work or help with other versions of iOS.

How to create an SSL Certificate

Anonymous (anonymous@undisclosed.example.com) — 2026-03-23T10:18:43+00:00

How to create an SSL Certificate VPOP3 Enterprise supports SSL certificates for encrypted sessions. The basic mechanism to create an SSL certificate is that you have to generate a CSR (Certificate Signing Request) then send that to a CA (Certificate Authority) who will sign your certificate and give you the certificate back.

Data stream contained NUL character

Anonymous (anonymous@undisclosed.example.com) — 2018-11-14T10:45:49+00:00

Data stream contained NUL character Description of the problem NUL characters (bytes with value 0) are not allowed in email messages and should not be transmitted over POP3, SMTP or IMAP4 except in certain circumstances. If an attachment contains such a byte it must be encoded using

-ERR Password supplied for "xx" is incorrect

Anonymous (anonymous@undisclosed.example.com) — 2018-11-14T10:45:49+00:00

-ERR Password supplied for "xx" is incorrect If you receive a 'POP3 Client Error' something like: -ERR Password supplied for “xx” is incorrect this means that the password on the 'In Mail' tab in VPOP3 for the indicated user is entered incorrectly.

Error expanding recipient - Nesting Level too deep

Anonymous (anonymous@undisclosed.example.com) — 2018-11-14T10:45:49+00:00

Error expanding recipient - Nesting Level too deep You receive an error message saying: Error expanding recipient "" Nesting Level too deep (51) Check the configuration for loops (Note the '51' number may be slightly different - that's the nesting level - anything over 50 is detected as an error)

Setting up VPOP3 to work with Exchange 2003

Anonymous (anonymous@undisclosed.example.com) — 2018-11-14T10:45:49+00:00

Setting up VPOP3 to work with Exchange 2003 The instructions below are for Exchange Server 2003. For other versions of Exchange see here. You can link VPOP3 to Exchange Server, so that Exchange Server sends outgoing mail through VPOP3 and VPOP3 sends any incoming mail directly to Exchange Server.

French Webmail Language File

Anonymous (anonymous@undisclosed.example.com) — 2018-11-14T10:45:49+00:00

French Webmail Language File Copy/paste the text below to a file 'french.lng' or 'francais.lng' in the VPOP3 directory. (French users, feel free to update/correct the text below) #login page logintitle=VPOP3 Login webadminlogin=web admin login webmaillogin=web mail login enterusername=You must specify your VPOP3 username here bookmarksnotsupported=I'm sorry, but your web browser does not support this function. You will have to add this page to your bookmarks manually. loginfailed=Login Faile…

German Webmail Language Page

Anonymous (anonymous@undisclosed.example.com) — 2018-11-14T10:45:49+00:00

German Webmail Language Page Copy/paste the text below to a file 'german.lng' in the VPOP3 directory. (German users, feel free to update/correct the text below) #login page logintitle=VPOP3 Login webadminlogin=web admin login webmaillogin=Webmail Anmeldung enterusername=Sie müssen einen Benutzernamen angeben bookmarksnotsupported=I'm sorry, but your web browser does not support this function. You will have to add this page to your bookmarks manually. loginfailed=Anmeldung fehlgeschlagen …

Setting up an iPhone/iPad/iPod Touch

Anonymous (anonymous@undisclosed.example.com) — 2018-11-14T10:45:49+00:00

Setting up an iPhone/iPad/iPod Touch To set up an iPhone to access VPOP3's mail, you first of all need to configure VPOP3 to allow access by remote users (unless you will only be using the iPhone in the office, connected via WiFi to the office LAN). Adding the mail account to your iPhone/iPad

Out of Disk Space When Sending Mail

Anonymous (anonymous@undisclosed.example.com) — 2018-11-14T10:45:49+00:00

Out of Disk Space When Sending Mail The first thing you should do is check that there is enough free disk space on the disk where VPOP3 is installed. VPOP3 requires a certain amount of free space before it will allow new messages to be sent, so the disk might not be totally full, but VPOP3 will still report that there is insufficient disk space when you try to send a new message. This buffer zone is designed to help prevent the disk totally filling up, which can cause lots of bigger problems!

VPOP3 - POP3 Client Connection Problem

Anonymous (anonymous@undisclosed.example.com) — 2018-11-14T10:45:49+00:00

VPOP3 - POP3 Client Connection Problem These errors occur during the period when VPOP3 is trying to establish a connection to your ISP's POP3 mail server to receive incoming mail. They can mean that you have entered the POP3 Server address incorrectly, or that there is a problem with the network, or that your ISP's mail server is not working properly.

VPOP3 - POP3 Client Problem

Anonymous (anonymous@undisclosed.example.com) — 2018-11-14T10:45:49+00:00

VPOP3 - POP3 Client Problem These errors occur whilst VPOP3 is communicating with your ISP's POP3 mail server to retrieve your mail. The server connection was closed unexpectedly If the message text is Error with Pop3 Client (XXXX (YY)) The server connection was closed unexpectedly

Spam Quarantine

Anonymous (anonymous@undisclosed.example.com) — 2018-11-14T10:45:49+00:00

Spam Quarantine By default, when the VPOP3 spam filter detects a message as being spam, it will go to the user's quarantine. Users can release messages from the quarantine by going to their webmail page and selecting the message from the quarantine list there.

Sender Domain Must Resolve

Anonymous (anonymous@undisclosed.example.com) — 2018-11-14T10:45:49+00:00

Sender Domain Must Resolve If you receive an 'SMTP Client Error' something like: 451 (user@domain.com) Sender Domain Must Resolve this means that the ISP's mail server cannot find the domain.com part of the email address. Often this means that the FROM address of the message is invalid, or that the

Sender Policy Framework / SPF

Anonymous (anonymous@undisclosed.example.com) — 2018-11-14T10:45:49+00:00

Sender Policy Framework / SPF SPF is a system used to tell mail servers which IP addresses can send mail from which domains. It is designed to reduce 'spoofing' of email addresses. For instance, if you receive an email message from your bank, your mail software can check that it came from an IP address authorised to send mail from your bank, and treat the message with suspicion if it didn't come from an authorised IP address.

Timeout problems downloading/uploading messages with attachments

Anonymous (anonymous@undisclosed.example.com) — 2018-11-14T10:45:49+00:00

Timeout problems downloading/uploading messages with attachments There are various possible reasons for this, usually to do with third party internet security software but they may also be associated with Windows TCP/IP or dial-up adapter issues. You may not have problems with other software, but that doesn't mean the problem is being caused by VPOP3.

Using a Mobile Phone with VPOP3

Anonymous (anonymous@undisclosed.example.com) — 2018-11-14T10:45:49+00:00

Using a Mobile Phone with VPOP3 Many people want to use a mobile phone to send/receive their email nowadays. This is usually easy to do with VPOP3. The recommended way is to have the phone connect directly to VPOP3 for sending/receiving email. To do this, you need to do three things:

Using VPOP3 with Microsoft Exchange Server

Anonymous (anonymous@undisclosed.example.com) — 2018-11-14T10:45:49+00:00

Using VPOP3 with Microsoft Exchange Server You can link VPOP3 to Exchange Server, so that Exchange Server sends outgoing mail through VPOP3 and VPOP3 sends any incoming mail directly to Exchange Server. You should first of all set up VPOP3 to send and receive Internet email as described in the online help.

Error message: VPOP3 Alert - Non-existent user -

Anonymous (anonymous@undisclosed.example.com) — 2018-11-14T10:45:49+00:00

Error message: VPOP3 Alert - Non-existent user - If you receive an error message like: Subject: VPOP3 Alert - Non-existent user - Delivery Failure Report. There was incoming mail for non-existent user "". This means that VPOP3 downloaded a message using POP3 and it was addressed to an email address which does not exist.

VPOP3 Antivirus Update Error - Error 11

Anonymous (anonymous@undisclosed.example.com) — 2025-10-06T15:24:19+00:00

VPOP3 Antivirus Update Error - Error 11 If you receive an “Error 11” when VPOP3 Antivirus is attempting to upgrade, then this means that it cannot download the antivirus updates from the Internet * Make sure you are using the latest version of the VPOP3AV plugin. You can check the version in the Settings

VPOP3 Antivirus Update Error - Error 55

Anonymous (anonymous@undisclosed.example.com) — 2018-11-14T10:45:49+00:00

VPOP3 Antivirus Update Error - Error 55 If you receive an “Error 55” when VPOP3 Antivirus is attempting to upgrade, then this means that the virus definition database is not readable. If you have VPOP3 Antivirus version 1.0.6 or earlier (check on Settings

VPOP3 Not Starting Properly

Anonymous (anonymous@undisclosed.example.com) — 2018-11-14T10:45:49+00:00

VPOP3 Not Starting Properly If VPOP3 is not starting properly, then the first thing to check is whether the database server is starting. In VPOP3 v3 and later, VPOP3 uses a PostgreSQL Database server for data storage, so if the database server is not running, VPOP3 will not be able to start properly. In this case, the VPOP3.EXE process may appear in Task Manager, but it won't respond to anything, or it may appear in Task Manager and then stop after a short period.

VPOP3 re-downloading old messages from the ISP POP3 server

Anonymous (anonymous@undisclosed.example.com) — 2026-01-05T09:31:47+00:00

VPOP3 re-downloading old messages from the ISP POP3 server If you tell VPOP3's POP3 mail collector to leave messages on the ISP's server for a few days, you may find that sometimes VPOP3 will redownload all the messages from the ISP mailbox again.

When sending mail, VPOP3 adds 'PRVS=...' to the sender address

Anonymous (anonymous@undisclosed.example.com) — 2018-11-14T10:45:49+00:00

When sending mail, VPOP3 adds 'PRVS=...' to the sender address This is because VPOP3 version 5 and later support BATV. BATV helps to eliminate 'backscatter spam', where someone else sends spam pretending to be from you, and then you receive all the bounce messages from those messages. BATV encodes the sender address in a special way so that VPOP3 can detect that a bounce message is in response to a message that you actually sent.