https://wiki.pscs.co.uk/ 2026-05-06T12:33:33+00:00 https://wiki.pscs.co.uk/ https://wiki.pscs.co.uk/_media/wiki:dokuwiki.svg text/html 2018-11-14T10:45:49+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.pscs.co.uk/how_to:550_not_permitted?rev=1542192349&do=diff 550/553 Not Permitted error from BT Internet's mail servers BT Internet's mail servers only allow messages to be sent from 'approved' email addresses. If you try to send messages from other addresses BT's mail servers may return a '550 Not Permitted' error, a '553' error, or may silently discard the message depending on what their server feels like doing today. text/html 2018-11-14T10:45:49+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.pscs.co.uk/how_to:incoming_smtp_feed?rev=1542192349&do=diff Incoming SMTP Feed An incoming SMTP feed is where incoming mail is sent directly to your mail server without going through your ISP's POP3 mail server on the way. Advantages An incoming SMTP feed has several advantages over going via a POP3 mailbox: text/html 2018-11-14T10:45:49+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.pscs.co.uk/how_to:backscatter?rev=1542192349&do=diff 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 text/html 2018-11-14T10:45:49+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.pscs.co.uk/how_to:no_transport_provider_is_available?rev=1542192349&do=diff Outlook/Windows Messaging reports "No transport provider is available" If Outlook or Windows Messaging reports No transport provider is available when trying to connect to VPOP3, it can mean several things. (This must be a contender for “the world's most meaningless error message text/html 2018-11-14T10:45:49+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.pscs.co.uk/how_to:vpop3_sending_high_volumes_of_unrecognised_mails?rev=1542192349&do=diff SMTP Relay Protection in VPOP3 SMTP Relay Protection should be used on ALL SMTP mail servers (such as VPOP3) which have a permanent connection to the Internet. You may also want to use it on servers which are only connected occasionally via a dial-up connection. text/html 2018-11-14T10:45:49+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.pscs.co.uk/how_to:10503?rev=1542192349&do=diff Socket Error 10503 - No More Data Error 10503 means that the connection between VPOP3 and a remote computer (normally your ISP) was dropped at an unexpected time. This is different from the error 10054 in that this is a controlled line drop. One way this can happen is if the ISP's POP3 server uses an obsolete standard which allows it to drop the connection if a POP3 'LIST' command is performed on an empty mailbox. The current standard requires that the connection is not dropped until the clien… text/html 2018-11-14T10:45:49+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.pscs.co.uk/how_to:allow_remote_access_to_vpop3_mailboxes?rev=1542192349&do=diff Allow Remote Access to VPOP3 Mailboxes Sometimes people want to be able to access their office VPOP3 mail server from a remote site or mobile phone etc. These instructions assume you have a permanent Internet connection (eg ADSL, Cable etc). If you don't have a permanent Internet connection, see text/html 2018-11-14T10:45:49+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.pscs.co.uk/how_to:create_a_mail_sender?rev=1542192349&do=diff How to create a Mail Sender In VPOP3 a Mail Sender tells VPOP3 how to send mail out to another mail server, usually for sending mail across the Internet. To create a mail sender, go to the VPOP3 Settings, then Mail Connectors. In the Mail Senders section on the left, choose text/html 2018-11-14T10:45:49+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.pscs.co.uk/how_to:encrypt_sessions?rev=1542192349&do=diff How To Encrypt Sessions VPOP3 Enterprise 2.6 and later supports SSL/STARTTLS encrypted sessions to VPOP3 itself. So, the email client or web browser will encrypt the data passed to VPOP3 so it cannot be intercepted. This requires an SSL Certificate to be created for VPOP3. text/html 2018-11-14T10:45:49+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.pscs.co.uk/how_to:exchange_2003?rev=1542192349&do=diff 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. text/html 2018-11-14T10:45:49+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.pscs.co.uk/how_to:isp_needs_ssl_connection?rev=1542192349&do=diff ISP needs SSL connection A few ISPs use a non-standard and not recommended system of encrypting connections to their SMTP mail servers. These generally are called 'SSL' connections and work on an alternate port other than the standard SMTP port 25. (The correct way to encrypt connections is to use a system called TLS which works on the standard SMTP port). text/html 2018-11-14T10:45:49+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.pscs.co.uk/how_to:mozilla_thunderbird?rev=1542192349&do=diff How to configure Mozilla Thunderbird This article won't show you all the possible settings in Thunderbird, because there are so many. Thunderbird is one of the most powerful & flexible email clients available at the time of writing, especially if you use IMAP4 (with VPOP3 Enterprise). text/html 2018-11-14T10:45:49+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.pscs.co.uk/how_to:sender_domain_must_resolve?rev=1542192349&do=diff 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 text/html 2018-11-14T10:45:49+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.pscs.co.uk/how_to:sender_policy_framework?rev=1542192349&do=diff 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. text/html 2018-11-14T10:45:49+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.pscs.co.uk/how_to:sending_mail_through_your_gmail_account?rev=1542192349&do=diff Sending mail through your Gmail account According to Google, the settings for sending mail through Gmail are: Outgoing Mail (SMTP) Server - requires TLS or SSL: smtp.gmail.com (use authentication) Use Authentication: Yes Port for TLS/STARTTLS: 587 Port for SSL: 465 text/html 2018-11-14T10:45:49+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.pscs.co.uk/how_to:using_vpop3_with_microsoft_exchange?rev=1542192349&do=diff 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. text/html 2018-11-14T10:45:49+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.pscs.co.uk/how_to:vpop3_access_security?rev=1542192349&do=diff How To Setup VPOP3 Service Security VPOP3 can be configured to restrict access to its various services depending on the client computer's IP address. This is useful if you want to allow access from only certain IP addresses (eg within your LAN) and prevent access from other IP addresses (eg the Internet). text/html 2018-11-14T10:45:49+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.pscs.co.uk/how_to:vpop3_deleting_messages_as_old_messages?rev=1542192349&do=diff VPOP3 Deleting messages as 'old' messages If VPOP3 says 'deleting old message' in the status window activity log that means that it has seen the unique ID of that message before, longer ago than the time specified for VPOP3 to leave messages on the server, so it thinks that the message is an old message, and so deletes it. text/html 2018-11-14T10:45:49+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.pscs.co.uk/how_to:vpop3_xxxxx_server_access_not_allowed?rev=1542192349&do=diff VPOP3 Server Access Not Allowed If you get an error like: -ERR VPOP3 Server access not allowed! when trying to access VPOP3, then this means that the relevant server's IP Access Restrictions defined in VPOP3 do not allow access from your client computer. text/html 2018-11-14T10:45:49+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.pscs.co.uk/how_to:421_4.3.2_vpop3_too_many_connections_from_your_ip_address_-_try_later?rev=1542192349&do=diff 421 4.3.2 VPOP3 Too many connections from your IP address - try later If you see this error message when you are sending messages, then it means that VPOP3 has detected too many simultaneous connections from your IP address. This would usually happen if the sender is another mail server as they can make many simultaneous connections when there are lots of messages to send. The error code that VPOP3 gives means that the sender should try sending the messages later, so it should be possible to e… text/html 2018-11-14T10:45:49+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.pscs.co.uk/how_to:11002?rev=1542192349&do=diff Socket Error 11002 - Host not found (Non-Authoritative answer) This means that VPOP3 is not getting a response from a DNS server when it is trying to look up the name of the ISP's mail server(s). Usually this means that Windows either does not know the address of a valid text/html 2018-11-14T10:45:49+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.pscs.co.uk/how_to:backup_vpop3?rev=1542192349&do=diff How to Backup VPOP3 By default VPOP3 v3 and later will automatically perform a daily backup of the database into a file called DBBACK-x.DMP, where the backup file rotates on a weekly basis (DBBACK-0.DMP is Sunday's backup, DBBACK-1.DMP is Monday's backup, etc). text/html 2018-11-14T10:45:49+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.pscs.co.uk/how_to:database_disk_caching?rev=1542192349&do=diff Database & Disk Caching Disk Caching One key point is that, like all other high-end databases, PostgreSQL should not be run on a server with disk level write back caching. With write back caching, the disk will report data as being written to disk when it is still in the disk's cache memory. If the power then fails, this data is lost and can cause database corruption. As long as the database server really knows when the data has been written to disk, power failure will not cause database corru… text/html 2018-11-14T10:45:49+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.pscs.co.uk/how_to:database_maintenance?rev=1542192349&do=diff Database Maintenance VPOP3 uses the PostgreSQL database server for most of its data storage. Normally this will not require any special maintenance, because it will manage itself. To do any special database maintenance you will need to close down VPOP3 first, because PostgreSQL needs exclusive access to the database to perform any operations such as decreasing the size of database files. Note that these operations may take some time! There are some PostgreSQL utility programs in the VPOP3\pgs… text/html 2018-11-14T10:45:49+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.pscs.co.uk/how_to:database_size?rev=1542192349&do=diff VPOP3 Database Size The VPOP3 directory is stored in the VPOP3\pgsql\data folder and subfolders. If you are concerned about the size of the VPOP3 database, there are several factors which may make the database larger than you would expect: * The VPOP3 database contains a lot more information than just messages in mailboxes. This can include settings, outgoing messages, historical logging information, statistical information for the spamfilter, information about archived messages, etc. Also,… text/html 2026-03-26T13:24:06+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.pscs.co.uk/how_to:dns_servers_for_internal_external_access?rev=1774531446&do=diff text/html 2025-10-06T15:21:37+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.pscs.co.uk/how_to:error_messages?rev=1759764097&do=diff Error Messages This is the place to look if you are trying to trouble shoot a problem and you have received or have access to a specific error message or error code. If instead your problem is that something you think is set up correctly is not working then the best place to look would be the text/html 2018-11-14T10:45:49+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.pscs.co.uk/how_to:exchange_2007?rev=1542192349&do=diff 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. text/html 2018-11-14T10:45:49+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.pscs.co.uk/how_to:installation_checklist?rev=1542192349&do=diff Installation checklist This list contains some things you may want to check before or after installing VPOP3 to make sure it's not going to encounter any common issues. Before installation * Make sure that VPOP3 is not installed on a RAID 5 or RAID 6 array. text/html 2018-11-14T10:45:49+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.pscs.co.uk/how_to:invalid_helo_name?rev=1542192349&do=diff SMTP error 'Invalid HELO name' When sending mail you may get an error from the remote SMTP server saying something like 'Invalid HELO name' This happens if the host name configured in VPOP3 does not look like a valid Internet host name (e.g. 'mail.domain.com'). Some SMTP servers don't bother checking this value because it has no authentication value at all, but a few do check that it looks correct. text/html 2018-11-14T10:45:49+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.pscs.co.uk/how_to:isp_needs_pop3_before_smtp_authentication?rev=1542192349&do=diff The ISP needs POP3 before SMTP authentication Some ISPs (especially in Germany) require you to log on to collect your POP3 mail before they will allow you to send any mail through their SMTP relay servers. VPOP3 actually connects to the POP3 server and SMTP server at the same time, so usually it will not have successfully logged onto the ISP's POP3 server before it tries to start sending mail. text/html 2018-11-14T10:45:49+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.pscs.co.uk/how_to:isp_needs_you_to_connect_on_port_587?rev=1542192349&do=diff ISP needs you to connect on port 587 Some ISPs will need you to send mail using port 587, instead of port 25. Port 587 is the 'SMTP Submission' port which is commonly used instead of, or as well as, the standard SMTP port 25 for when users are sending mail to a smart host/relay server. text/html 2018-11-14T10:45:49+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.pscs.co.uk/how_to:limit_size_of_sent_mail?rev=1542192349&do=diff How to limit size of sent mail There are several ways to limit the size of mail which can be sent * Limit the size of mail accepted by the SMTP component of VPOP3 * Limit the size sent for a particular user * Limit size based on 'rules' * Limit size based on text/html 2018-11-14T10:45:49+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.pscs.co.uk/how_to:performance_requirements?rev=1542192349&do=diff Performance Requirements The performance requirements for VPOP3 depends on many factors, so we can't give specific details for any scenario. How to detect limiting factors * Use the Windows Performance Monitor (perfmon.msc) * Add counters for: text/html 2018-11-14T10:45:49+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.pscs.co.uk/how_to:problems_sending_mail_via_bt_from_your_own_domain?rev=1542192349&do=diff Problems sending mail via BT from your own domain BT Internet only allow you to send mail through their mail servers from your BT Internet address or other registered address. Attempts to send from other addresses will give you a 553 SMTP error message. text/html 2018-11-14T10:45:49+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.pscs.co.uk/how_to:route_mx_sent_direct_outbound_mail_through_your_isp_s_relay_server?rev=1542192349&do=diff Route MX Sent (Direct) Outbound Mail Through Your ISP Some mail providers (for example Hotmail, AOL and GMail) will reject mail sent from servers running on dynamic IP addresses. It is possible to route such mail through your ISP's relay server whilst still sending most mail direct to the recipient server using MX text/html 2018-11-14T10:45:49+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.pscs.co.uk/how_to:smtp_client_problem?rev=1542192349&do=diff VPOP3 - SMTP Client Problem These errors occur whilst VPOP3 is communicating with your ISP's SMTP mail server to send your mail. If the message text is: Error with SMTP Client (XXXX (YY)) The server connection was closed unexpectedly Then this means that the the connection between VPOP3 and your ISP's SMTP mail server was closed when VPOP3 did not expect it to be. This can be caused by the network connection failing or a bug in the ISP's mail server which drops the connection in abnormal circ…