Voicemail to email

I have an asterisk server running sendmail on centOS. Is there a trick to have asterisk sendmail is working fine when I tell it to send a message from the command line. However my voicemails are not being sent to email… They seem to only be send sparatically .

All of the extensions are set up in the voicemail.conf with email addresses.

is there a log I can check ?
or a tweak in a file that anyone may know of?

Thank You