Deliverability depends on your sending setup and your reputation. Set up SPF, DKIM and DMARC records on your domain. Send from your own domain, not a free email address. Keep your list clean and send content people open.
A list that stops opening hurts your reputation. Remove people who have not opened in months.
Do it step by step
- Add SPF, DKIM and DMARC records for your sending domain.
- Warm up a new domain slowly.
- Ask new subscribers to reply or add you to contacts.
- Clean inactive subscribers every few months.
- Test emails with a spam checker before big sends.