Most of the host restrict to send emails. But you want to send email to all users. Here Front End PM PRO has two very useful options.

Sending Interval: You can set interval of send email for announcement emails.

Emails send per interval: How many announcement emails will be sent per interval

Example: You set Sending Interval = 60 and Emails send per interval=100. So in every 60 minutes announcement email will be sent to 100 users.

 
Version 5.1 or more you can see how many emails already sent by go to Dashboard > Front End PM PRO > All Announcements

Screenshots: