bMail has a feature to allow another person access to your e-mail account: this allows them to send, read and delete messages. For example, a spouse, admin or co-worker may need continued access for various reasons, so the ability to delegate account rights to them in certain situations may be critical (especially in the case of departmental accounts).
Delegated access in bMail allows others to handle ones e-mail, however it disallows them from changing your password, using chat, or changing misc. account settings. Further, only up to 25 users may be granted this type of access at any one time.
To set up mail delegation, log into the account you would like to delegate (how to log into a Special Purpose Account/SPA) and follow the instructions provided by Google: https://support.google.com/mail/answer/138350?hl=en.