This may not be advertised and done enough because of its technical aspect, but setting your DNS records is an important step in making your overall deliverability better.
SPF (Sender Policy Framework)
Only if you use Overloop with a Google account:
Simply put, your SPF defines which IP addresses can be used to send emails from your domain.
Servers are like messengers, passing on mail from you to your recipient. By setting your SPF–which can only be done from your own domain–your sending server can prove to your recipient’s receiving server that you gave it permission to transmit an email on your behalf. If you don’t, it could make emails bounce back.
We, here at Overloop–as well as most of our customers–deliver emails through Google’s servers; so here are their instructions on how to set your SPF.
It’s unfortunately impossible to make a step-by-step guide for DNS settings since the process depends on every domain host. Here are, nonetheless the link to the instructions for some of the most popular ones:
Amazon Web Services: Configuring DNS, Resource Record Types
GoDaddy: Add a CNAME Record
Google Domains: DNS Basics
Hostgator: Manage DNS records
Hover: Edit DNS Record
Namecheap: SPF & DKIM
Squarespace: Advanced DNS Settings
Stablehost: How do I get to cpanel?
DKIM (DomainKeys Identified Mail)
Much like SPF, DKIM is a way to identify you as the real sender of the email. It works as some kind of seal.
You’re actually setting up two keys:
A private one, which is encrypted, unique to your domain, only available to you and which you use to encrypt your signature in the header of your emails
A public one, which you add to your DNS records using DKIM standard to allow your recipient’s server to retrieve it and decrypt your hidden signature from the header of your email
Again, if you’re using Google, here's their guide. For the rest, it depends on your domain host.