• The PYTHEAS MailGate service does not start at system start-up
• Messages sent to public folders by PYTHEAS MailGate are stored as a post (IPM.Post), not as a message (IPM.Note) as expected
• Messages sent to a Microsoft Exchange 2007 distribution list are not distributed
• Incoming messages from certain POP3 servers are not correctly decoded by Microsoft Exchange 200x
• The PYTHEAS MailGate Communication Task does not work as expected when running as a service, but works as expected when launched from the Start menu
• The PYTHEAS MailGate Communication Task stops working unexpectedly
• Certain kind of attachments in outgoing messages appear corrupted (with Microsoft Exchange server)
• Timeout error with empty POP3 mailbox
• The PYTHEAS MailGate Communication Task stops working randomly after finishing mail download from the last POP3 account
• Messages delivered to a mailbox abnormally grow in size
• Virus scanner interface: disabled size limit does not work as expected
• Problem when sending outgoing messages to a server which does not support ESMTP protocol extensions
• Session log messages sent to remote locations grow in size

To configure the dependency, proceed as follows:
- Open Regedt32.exe (not Regedit.exe);
- Go to HKEY_LOCAL_MACHINE/System/Currentcontrolset/Services/Pytheas.MailGate
- Open the DependOnService value. By default, it has 3 lines: Eventlog, RpcSc, TcpIp.
- Add the line: POP3Svc to the end of the list. This will make the Pytheas.Mailgate service dependent on this service.

You can reproduce this problem with the Send test message function on the Recipient property page of the Recipient pointing to the distribution list. The SMTP dialog completes normally.

Please note that this is a Microsoft Exchange 2007 feature, not a PYTHEAS MailGate problem.

Historical note: this problem has been observed first with British Telecom BTConnect POP3 accounts, hence the choice of the keyword.

The Microsoft Exchange Server (v. 5.0 or v. 5.5)  can be forced to do the MIME encoding in base64 which is widely supported. To change the default behaviour you need to edit the registry (please be careful using the registry editor...)

Go to the following key:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\...
...Services\MSExchangeIS\ParametersSystem\...
...InternetContent

Add the value ForceBase64 of  data type REG_DWORD with value 0x1. Then restart the Microsoft Exchange server Information Store service (and any dependent services).

From: Microsoft Knowledge Base, Article ID: 182307 (Article last modified on 05-Nov-2004).

The POP3 server does not conform to RFC 1939. Use the Try connection button of the Configuration Program, POP3 account property page, to see the POP3 dialog when the mailbox is empty. Check if you get a dialog like:

+OK IMS POP3 Server 0.87 Ready
USER username
+OK username is welcome here
PASS xxxxxxxxxxx
+OK username's mailbox has 0 message(s) (0 octets)
LIST
+OK 0 message (0 octets)
0 messages (0 octets)

The problem is that the "0 messages (0 octets)" line should not be there, and that the response to the "LIST" command is not terminated by a single point on a line.
Here is what RFC 1939 (POP3, May 1996) says on the subject (we did the bold typesetting):

(...)
Responses to certain commands are multi-line. In these cases, which are clearly indicated below, after sending the first line of the response and a CRLF, any additional lines are sent, each terminated by a CRLF pair. When all lines of the response have been sent, a final line is sent, consisting of a termination octet (decimal code 046, ".") and a CRLF pair.
(...)
LIST [msg]
Arguments: a message-id (optionally) If a message-id is given, it may NOT refer to a message marked as deleted.
Restrictions: may only be given in the TRANSACTION state.

Discussion:
If an argument was given and the POP3 server issues a positive response with a line containing information for that message. This line is called a "scan listing" for that message.
If no argument was given and the POP3 server issues a positive response, then the response given is multi-line. After the initial +OK, for each message in the maildrop, the POP3 server responds with a line containing information for that message. This line is called a "scan listing" for that message. If there are no messages in the maildrop, then the POP3 server responds with no scan listings--it issues a positive response followed by a line containing a termination octet and a CRLF pair.

The problem occurs when both of the following conditions are met:

• the product is configured to take care of outgoing mail
• a session log message is sent to a remote location (as configured on the Logging tab of the Configuration Program).