Difference between integrating gmail into CRM and using Mail Module

Difference between integrating gmail into CRM and using Mail Module

We would like to use Mail Application eventually however having trouble getting more than one user recognised by one phone number.

In the meantime I thought we could use the Gmail integrations into the CRM and when the first issue is resolved install mail application and continue on.

Howver we have had a mess of an introduction re Books versus CRM invoices so I am cautious in regards to whether adding the Gmail/Integration will be a backward step and I should wait till the first issue is resolved.

Regards
Robin