The answer is NO, unless a limit is set by your provider.
If your provider has a limit of 70 recipients, in Mailbird you will also only be able to send to 70 recipients.
Mailbird is not deigned to be a bulk email solution. Mailbird is an upgraded email experience when compared with the likes of Windows Mail, Outlook and Thunderbird.
If you're looking for a bulk email solution, then you should consider products like Mailchimp, Madmimi or perhaps Sendgrid.