Simple Mail Transfer Protocol - network protocol used for the secure transfer of e-mails between the PBX and external mail servers. The PBX needs an external SMTP server (outgoing mail server) to send system e-mails or forward voice mail messages and fax messages.

Under Administration > E-mail > Outgoing mail serveryou can enter different outgoing mail servers. If no outgoing mail server has been entered, no e-mails can be sent.