Mailbox was designed to be the email control hub inside Pipedrive. Pipedrive supports all major providers (including Gmail, Outlook and also custom IMAP/SMTP). There are 2 options for syncing user emails: 2-way sync: Mail Connection is established with the mail provider (example Gmail). There can be only 1 active Mail Connection per user in company. 1-way sync: SmartBCC feature which stores the copies of email messages to Pipedrive by adding the SmartBCC specific address to mail recipients.