Programmable/scriptable mail server

I have the following scenario:

Users send email messages to the special mail addresses (each address is associated with a user). When the message arrives to the server I need to extract a certain information from the message body and store it in the database.

I am looking for a mail server (or client) that matches following conditions:

• Free/open-source
• Users/inboxes can be created/deleted via some API on the fly
• Works in unix/mac environment (Ubuntu/MacOS X in my case)
• Allows me to set up hooks on message queue (via API or receive the data via some I/O channel)
• Has good performance and开发者_StackOverflow社区/or scalability potential
• Does not have a dependency on Java or other heavy framework.

Note that I do not need a full-fledged mail server i.e. all I need is messages processing.

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Finally, I decided to use http://mailgun.net/ service which provides exactly what I need