A subscriber can restrict access to his Mail2Fax service with some methods, those can also be combined:
Secret Key: the secret key used to validate the sender of an e-mail; not used if left empty
Secret Key Renew: secret key renewal period; Sipwise C5 platform will enforce renewal of the secret key when the defined time has elapsed
Last Secret Key Modify Time: information about the last secret key modification time
Secret Key Renew Notify: an e-mail address where the notification about secret key modification is sent
ACL: access control list, see the details below; this is a list of access control rules
The parameters for access control rules:
From email: this sender is allowed to use Mail2Fax service
Received from IP: this IP address or host name must be present in From e-mail header
Destination: either a complete phone number in E.164 format, or a regular expression ("Use Regex" checkbox must be ticked) that may define a range of numbers. Examples: "4313334445" as a single number; "^4399.+" as a regular expression: all destinations starting with "4399"
When neither Secret Key, nor ACL is defined then Mail2Fax service will deny accepting any e-mail for sending faxes!