Set Requester based on Subject

Hi,

We would like to integrate this with Site24*7 which I understand is possible at the moment - in that it will sent alerts/notifications to ServiceDesk Plus automatically.
The problem is that all alerts will come from one email address (by default noreply@site247.com)

Is it possible to have the 'requester' be set based on a subject line perhaps?
Although we would somehow need to keep the ability for people to email in their requests and the tickets being assigned to the correct account based on their email domain.

Does anyone else here face a similar issue?
The easy answer would be for the tech to assign the ticket manually, but its one step I would like to get rid of if possible.

Thanks

Michael.