This article describes that reply-to option on the email server is no longer available on 7.4.4 and later.
Scope
Fortigate v7.4.4 and later.
On FortiOS 7.4.4 and later, the reply-to has been set automatically to [email protected] in the email server settings. This will affect all SMTP servers, and even a custom SMTP server is included.
On a custom SMTP server like Office 365, it is necessary to have the same username and the same ‘reply-to’ sender. However, it will not be the same because the reply-to field is automatically changed to [email protected] once upgrading the device to v7.4.4 and later.
Here is the output on v7.4.4, the ‘reply-to’ option is no longer available and thus cannot be changed.
config system email-server set type custom set server "smtp.office.365.com" set port 587 set source-ip 0.0.0.0 set source-ip6 :: set authenticate enable set validate-server disable set username "[email protected]" set password ENC *** set security starttls set ssl-min-proto-version default set interface-select-method auto end
As a result, every attempt to send a FortiToken email will fail, and it will show the result of ‘buffer full’.
2024-05-24 12:32:34 sessionn 0xa16c070, SSL connected 2024-05-24 12:32:34 session: 0xa16c070, rsp_state: ehlo, code: 250 2024-05-24 12:32:34 session: 0xa16c070, rsp_state: auth, code: 334 2024-05-24 12:32:34 session: 0xa16c070, rsp_state: auth2, code: 235 2024-05-24 12:32:34 session: 0xa16c070, rsp_state: mail, code: 250 2024-05-24 12:32:34 session: 0xa16c070, rsp_state: rcpt, code: 250 2024-05-24 12:32:34 session: 0xa16c070, rsp_state: data, code: 354 2024-05-24 12:32:34 buffer is full 2024-05-24 12:32:34 _session_on_destroy 2024-05-24 12:32:34 <== send mail failed, m = 0xa151cc0 s = 0xa16c070
Solution
Use the default FortiGate SMTP server or in custom but set the same username to [email protected].
Note: To use the default Fortinet email server, it is necessary to register the device on FortiCare support and have an active contract.