E-mail to Salesforce
Salesforce allows your reps to send an e-mail to leads, contacts, and person accounts. Some of them prefer Salesforce to send e-mails, but some prefer the company-provided third-party e-mail client to send e-mails, for example, Outlook 365, Google for Work, and so on.
If your reps send e-mails from Salesforce, then a copy of the e-mail will be saved as a record. If they use a third-party e-mail client, say, Outlook 365, to send e-mails to customers, then those e-mails will not be saved in Salesforce. If you want to keep a record of each e-mail sent from a third-party e-mail client to the leads, contacts, opportunities, and other records, use Email to Salesforce.
This allows you to keep a copy of each e-mail in Salesforce, for ...