FreePBX and Asterisk do not allow you to send voicemails and notifications to multiple email addresses. But, there is a way to do it. Here are the simple steps:

1. From a Linux command prompt, open the file /etc/aliases in your favorite text editor. Add a line to the end of that file, using a descriptive name that should not duplicate any of the names already in this file, nor the username of any users on the system. The line should look like this (this is just an example, obviously):
   foo: user1@gmail.com,user2@gmail.com
   Where foo can be replaced with any alias name you like that does not duplicate an existing alias or username.  You can add as many email addresses as you need, but they should be separated only by commas, and NO spaces other than the one between the alias name and the first email address.
2. From the Linux command prompt, run the command newaliases and make sure that no errors are reported (you should not see any output at all).
3. If you are running raw Asterisk, then wherever you would normally use a single email address, you can now use the alias name @localhost, for example, foo@localhost.
4. If you are using an old version of FreePBX then it may not allow you to use addresses ending in @localhost. In that case, from the Linux command prompt run the command hostname -f and then use the result of that in place of localhost in step 3.
5. You can repeat these steps as needed to create additional aliases for different users on your system.  You might want to use meaningful alias names, for example mikevm to send Mike’s voicemails to multiple addresses.
6. Don’t forget that if you are only sending voicemail notifications, and not the entire voicemail as an attachment, that many wireless companies have SMS gateway addresses that you can send an email to, that will convert the first 140 characters of the email to an SMS text message.  You can find a list of email address formats to use for this purpose in this article:  How To Send Email To Any Cell Phone (for Free)
7. This technique is not limited to Asterisk and FreePBX; it should provide a solution for any software that can’t seem to deal with more than one email address at a time.