The App acts as a regular email client and thus can be setup for any IMAP mailbox. For sending emails of a specific mailbox, the STMP method has to be selected as php mail() or sendmail wont work.
Example - Sending Emails fields
SMTP server: mail.domain.com
Port: 587
Username: support@domain.com
Password: Pass123456@789
Encryption: TLS
Example - Fetching Emails fields
Protocol: IMAP
SMTP server: mail.domain.com
Port: 993
Username: support@domain.com
Password: Pass123456@789
Encryption: SSL