I agree with Tim.
You may want to set your email up to use DMARC. After you set it up if you have not already your emails will be checked by the ISP and will ensure they are delivered. Not doing this will most likely get your email bounced and not delivered.
Here is the info for that:
https://dmarc.org/
I myself bought Google Suite for its email. It cost 5 USD a month and I use it on a second domain name that is pointed to my main domain so I only have to buy one email from Google. After setting up SPF, DKIM and DMARC we no longer get placed in spam or bounces unless someone miss types their email address at signup.
Most shared web servers have users that abuse their email system and even if you have a static IP address for your host you are most likely sharing the email server. It is a huge drawback to shared web hosting and cloud web services.
If your server enforces local SMTP connections I would install Postman SMTP and enable the Gmail API feature. It is one of the best ways to get around shared hosts that force local SMTP mail only.
If you need to send thousands of emails per day I would suggest the same as above on Gmail using the SPF, DKIM and DMARC but I would use SendGrid with their API instead of Postman SMTP.
You will also have to set up SendGrid with SPF, DKIM and DMARC on your web sever so it is authenticated with your IP Address, otherwise you will be in a worst mess than not having anything set up as all emails will be tagged as phishing and you do not want that.
I hope this helps, email is one of the things you do not want failing. We have had great results with both Gmail and SendGrid.