POP3

The Axigen Solution: Overview & Architecture

Axigen POP3 module establishes connection with POP3 clients and retrieves mail messages from the storage unit. The server accepts connections as specified by the POP3 listeners defined in the configuration file. By default the server accepts connections on 127.0.0.1:110 .

POP3 module overview

In Axigen the POP3 module works as follows:

  • shows only the messages that existed in the mailbox when the mailbox was opened;
  • keeps zombie copies for the messages deleted during the current session; the module shows them as zero size messages, and the module reports an error when a client application tries to retrieve a deleted message;
  • messages are retrieved using the RETR command and the message is marked with the "Seen" flag (you can view this flag when using an IMAP or WebMail client).

The server only manages mail messages in Axigen Storage format. For more information on this format, please consult the Axigen Storage section.

Listeners

Listeners can be defined and managed to add extra flexibility and configurability to this service. For that, global access limitations, SSL Settings and access lists can be enforced on the address used by this service for binding.

Access control

Access rules allow you to control connection to this service by defining simple access lists for specific Networks / IP Ranges / IP’s. Service level access rules are automatically applied to all its listeners and will override for this service any existing Global Access rules.

Flow control

Flow control parameters can be adjusted to fine tune the server’s performance and avoid overloading it. Global access limitations to this listener can be enforced by setting the total number of simultaneous connections, concurrent connections from each remote IP address, number of new connections to the listener made in a time period interval, number of total connections from each remote IP address on a time interval period. The default interval for this time period is set to 1 minute.

Logging

All Axigen main services can log different types of events. You can specify what events are logged, where and how they are logged.

Encryption and authentication

Various authentication types can be used in Axigen for IMAP secured (SSL/TLS) or unsecured connections. Possible options are: normal login, plain, login, CramMD5, DigestMD5 and GSSAPI.

Error control

To protect the server, the number of failed/wrong commands received from POP3 clients during one session can be limited. When these limits are exceeded, incomplete connections or connections that are not RFC compliant will be dropped thus freeing important bandwidth.

If you do not specify a limit for the maximum number of (authentication) errors allowed for a POP3 client's session, security risks may arise.

Thread management

The Axigen mail server is designed to run on different machine configurations and operating systems, on networks with various traffic loads, structures, domain configurations, user rights etc. That is why, depending on all these variables, you can adapt the workload to the server’s processing power to improve its performance or avoid overload by setting the minimum and maximum number of threads that can be opened at a specific moment of time.

Compatibility with various POP3 mail clients

Axigen has been thoroughly tested and it is proven to work with Outlook, Thunderbird, Email Client OS X, Email Client Win 8.1