Do you know the figures, I mean, at what number I can get suspended?
Normally there is a limit of 500 emails per day and other limits which can be found here:
https://support.google.com/a/answer/166852?hl=enWhy not make a free account at mailchimp?
You can import all your contacts by csv, excel etc.
The newsletter templates are easy to use and free (up to 2k subscribers)
Also the newsletter are responsive (mobile ready)
Things get expensive when the total number of subscribers in all mailchimp list (on the same account) gets increased and if the number of subscribers is very high then OP should move to Amazon SES.