The property persistence.provider
The property persistence.provider

asynchronous.mail.default.attempt.interval = 300000l       // Five minutes
asynchronous.mail.default.max.attempts.count = 1
asynchronous.mail.send.repeat.interval = 60000l           // One minute
asynchronous.mail.expired.collector.repeat.interval = 607000l
asynchronous.mail.messages.at.once = 100
asynchronous.mail.send.immediately = true
asynchronous.mail.override = true
asynchronous.mail.clear.after.sent = false
asynchronous.mail.disable = false
asynchronous.mail.useFlushOnSave = true
asynchronous.mail.persistence.provider='hibernate'      // Possible values are 'hibernate', 'hibernate4', 'mongodb'
asynchronous.mail.gparsPoolSize = 1
asynchronous.mail.newSessionOnImmediateSend = false

asynchronous.mail.default.attempt.interval = 300000l       // Five minutes
asynchronous.mail.default.max.attempts.count = 1
asynchronous.mail.send.repeat.interval = 60000l           // One minute
asynchronous.mail.expired.collector.repeat.interval = 607000l
asynchronous.mail.messages.at.once = 100
asynchronous.mail.send.immediately = true
asynchronous.mail.override = true
asynchronous.mail.clear.after.sent = false
asynchronous.mail.disable = false
asynchronous.mail.useFlushOnSave = true
asynchronous.mail.useMongo = false
asynchronous.mail.gparsPoolSize = 1
asynchronous.mail.newSessionOnImmediateSend = false
