Currently I identify two options to start a process using email.
First one and probably the simpler is to design a process that will loop, query the email server to get list of emails in inbox and call Bonita Engine API to start a new process instance. To achieve such solution you would need to build a new connector that can use email protocol such as POP or IMAP to list messages in inbox. Same connector can also include call to API to create process instances. Main limitation is that each loop will lead to Bonita Engine information storage. You'll probably need to think about a policy to purge this history that is likely to be useless.
Second option is to use an ESB such as Apache Camel to take care of pooling the mail server. You'll need then to integrate API call to the ESB in order to create the Bonita instance. Main advantage here is that you probably get better performance and also can take benefit from an exsiting module of the ESB. Drawback is that you need to get familiar with the ESB configuration.
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