1

Set the MX record
required

Login to your domain provider, open the DNS editor, delete any MX record and add this one. It tells senders where to send emails for your domain.
Host / Name Value Priority
@ mail.postale.io. 0
2

Add 3 TXT records
recommended

Delete any existing TXT records for SPF, DKIM, and DMARC, and add these three. They will help your emails avoid SPAM folders.
Please specify a domain for DKIM and DMARC:
Host / Name Value
@ v=spf1 mx ~all
3

Add 2 CNAME records
optional

These records help email clients (Outlook, Thunderbird, ...) autoconfigure themselves from your credentials.
Host / Name Value
autoconfig mail.postale.io.
autodiscover mail.postale.io.