Is there a limit or quota on how many email messages I can send per day? Can I send more through an IMAP or POP client?
Regardless of which protocol used to send email, Google has imposed the following email sending limits (quota) to prevent abuse:
To send large volumes of emails to addresses outside of the Macalester domain, we recommend using group mailing lists, rather than individual email addresses.
Review Google's Sending limits guide for further information.