https://wiki.pscs.co.uk/ 2026-05-06T11:50:45+00:00 https://wiki.pscs.co.uk/ https://wiki.pscs.co.uk/_media/wiki:dokuwiki.svg 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: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:450_4.3.2_content_filter_timeout?rev=1542192349&do=diff 450 4.3.2 Content Filter Timeout If you get this error appearing when messages are sent to VPOP3, either in a bounce message, or in the VPOP3 status monitor, it means that the VPOP3 computer filter is taking more than the allowed amount of time (usually 60 seconds). text/html 2018-11-14T10:45:49+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.pscs.co.uk/how_to:550_5.7.1_relaying_not_allowed_bad_sender_ip_address?rev=1542192349&do=diff 550 5.7.1 Relaying not allowed! Bad sender IP address This SMTP error message means that the computer which is sending the message is not permitted to send outgoing messages based on the VPOP3 SMTP Service's Access Restrictions. This is probably because someone is trying to send messages from outside your local network, and you have not configured VPOP3 to allow this. You have to be careful when allowing this, because you may configure VPOP3 to be an open-relay, which is a 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: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:non-administrator?rev=1542192349&do=diff Trying to perform administrative tasks without rights This problem can have two symptoms: * When trying to access the VPOP3 settings you get an error “You are trying to perform an VPOP3 administration task while logged in as a non-administrator text/html 2018-11-14T10:45:49+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.pscs.co.uk/how_to:restricting_number_of_email_recipients_sent?rev=1542192349&do=diff Restricting the number of recipients sent to Some ISPs set restrictions on the number of recipients that you are allowed to send in a certain time period, eg 50 messages per hour, or the number of recipients that you are allowed to send per message or per connection. text/html 2018-11-14T10:45:49+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.pscs.co.uk/how_to:restricting_number_of_messages_sent?rev=1542192349&do=diff Restricting the number of messages sent Some ISPs set restrictions on the number of messages that you are allowed to send in a certain time period, eg 50 messages per hour, or the number of messages that you are allowed to send per connection. Restriction of messages per connection 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… text/html 2018-11-14T10:45:49+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.pscs.co.uk/how_to:smtp_rule_example_-_restrict_who_can_send_to_a_local_email_address?rev=1542192349&do=diff SMTP Rule Example - restrict who can send to a local email address If you have a local email address (a user, group or distribution list) and you want to restrict which email addresses can send messages to this address, you can use SMTP rules. There are a few ways you can configure the SMTP rules for this scenario. 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: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 2025-05-21T07:57:18+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.pscs.co.uk/how_to:allowing_mail_relay_through_vpop3?rev=1747814238&do=diff How To Allow Mail Relay Through VPOP3 If you are allowing remote access into VPOP3 to collect mail then you may also want those remote users to be able to send their outgoing mail through VPOP3 as well. This is more complex than allowing users to collect mail, because, by default, SMTP connections are not authenticated. This means that when someone tries to send a message through VPOP3, VPOP3 doesn't know who that user is. This can cause a problem if unauthorised users try to send mail through… text/html 2018-11-14T10:45:49+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.pscs.co.uk/how_to:data_stream_contained_nul_character?rev=1542192349&do=diff 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 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:vpop3_xxxxx_server_access_not_allowed_-_see_your_administrator?rev=1542192349&do=diff Error Message - VPOP3 xxxx Server Access Not Allowed - See Your Administrator If you get an error message when trying to connect to the VPOP3 SMTP/POP3/IMAP4/etc service which says VPOP3 xxxx Server Access not allowed - See your administrator (where xxxx is replaced with the specific service name, and there may be protocol specific error codes before the message) text/html 2018-11-14T10:45:49+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.pscs.co.uk/how_to:err_mailbox_locked?rev=1542192349&do=diff -ERR Mailbox Locked error If your email client displays an '-ERR Mailbox Locked' or '-ERR [IN-USE] Mailbox Locked' error when trying to log into VPOP3 it means that the mailbox is locked. The POP3 standard requires that POP3 mailboxes have an 'exclusive lock' on them when they are in use. This means that only one POP3 client can access the mailbox at once. Also, if a POP3 mailbox is currently accessing a mailbox, then no IMAP4, Webmail or administrator access is allowed to the mailbox at the s… text/html 2018-11-14T10:45:49+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.pscs.co.uk/how_to:error_message_after_sending_rcptto_-_error_0_-_text_550_5.7.1_relaying_not_allowed_bad_sender_ip_address?rev=1542192349&do=diff Error message after sending RCPTTO: - error 0 - text 550 5.7.1 Relaying not allowed! Bad sender IP address If you get this error message from within Webmail, then it usually means that the SMTP service access restrictions are blocking Webmail from sending mail. 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:install_the_status_monitor_on_other_pcs?rev=1542192349&do=diff How to install the VPOP3 Status Monitor on other PCs The VPOP3 status monitor icon is run by a separate program from VPOP3, which communicates with VPOP3 using TCP/IP. This means that this program can be installed on any PC which can connect to the VPOP3 computer using TCP/IP (on port 5109 by default). text/html 2019-02-06T17:10:31+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.pscs.co.uk/how_to:postgresql_replication?rev=1549473031&do=diff PostgreSQL Replication PostgreSQL 9.1 (used in VPOP3 5 and later) supports replication from a 'Master' to a 'Slave' database server. This can be used with VPOP3 for having a near-realtime backup of your settings & messages. To use the replication, you need to have a file share which is accessible from both PCs. The thing to watch out for is that the PostgreSQL services may be running as a different user from the currently logged in user, so make sure that the user(s) which the PostgreSQL servi… 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.