I am writing a web based application that needs to have some elements of CRM in it but I cannot use an of-the-shelf CRM to do what I want. (Honestly we have been through it all and it will not work).

Now while Tasks, Calls, Meetings and Notes are straightforward the idea of reinventing Mail and Calendars seems a waste of time and effort and also unproductive as most users already have their own and it simply adds to the complexity of my application and hacks users off.

My thoughts are going around using Outlook and or GMail/iCal and or Mac Mail/iCal and or Thunderbird and importing the relevant data or if possible integrating it into the application.

Any thoughts? Anyone got any experience of this can point me in a few directions.

N.B. Not looking for an answer as too complex just some pointers and thoughts. Thanks.

p.s. We did look at Sugar CRM as the basis for our project and it is useful to get best practice from but as I say it was not useable due to how we are structuring our software, not Sugar's fault.