In system email setup for P-Series PBX, STARTTLS is supported by default so don't enable the option 'TLS Encryption' if STARTTLS is implemented with smtp port 587. The option actually is for SSL encryption with smtp port 465, so when SSL encryption is implemented, the option 'TLS Encryption' have to be enabled.
Model: P-Series IPPBX
Firmware: Not required
If STARTTLS encryption is implemented with port 587, do not enable 'TLS Encryption' option.
If SSL encryption is implemented with port 465, please enable 'TLS Encryption' option.