Limit of the number e-mail recipients
If you are using the Webmail interface to send messages, there is a limit of 100 recipients total in the To:, Cc:, and Bcc: fields. This limit cannot be increased.
However, there are no limits on our end if you send e-mail through our SMTP server using some local mail client like Outlook, for example.
Another option to send a message to multiple recipients is to use mailing lists. They have been specifically designed to handle sending of a single message to many subscribers, and the number of recipients you send to is not limited. Mailing lists can be created on the "Mailing Lists" section of the Control Panel of the hosting account.