Hello there,
I checked your IP address, seems like you are not blacklisted yet on several email databases which are good news, as for Gmail, they will bounce any email that you send from the current IP unless you increase the positive reputation of the IP and make sure that you send quality emails, otherwise, there is a possibility that you will use this IP and you can not send emails from it.
In order to solve this problem that you have, I need to do the following:
1. Procced with an IP warmup process.
2. Clean your contacts list.
3. Send emails gradually until Gmail trust this IP that you are sending from.
4. Send in bulks afterward.
This process will take around a week, until you restore your IP reputation