Getting Undeliverable message while sending Non SMTP(fax addressing format ex:[RFAX:test@/FN=444]) address format from the desktop outlook client in enabled Use cached exchange mode setting of the user account.

Getting Undeliverable message while sending Non SMTP(fax addressing format ex:[RFAX:test@/FN=444]) address format from the desktop outlook client in enabled Use cached exchange mode setting of the user account like below screenshot 

if we disabled (uncheck) the above setting then i can able to send the Non SMTP(fax addressing format ex:[RFAX:test@/FN=444]) address format from the desktop outlook client.

our requirement is to send Non SMTP fax addressing format in Enabled "Use Cached Exchange Mode" setting of the User account from the desktop outlook client.

Could you please suggest any solution for resolving above problem.

Thanks in advance.

Regards,

Prasad.