Configuring DNS

One of the best features of poste.io is that it helps you set up your DNS in the best possible way to avoid having emails delivered to your SPAM folder.

All values are suggested, not required, and may not be best for your configuration, but should work as intended in most cases.

Server DNS

Log to administration: Server status → DNS diagnostics

1. PTR record

   The first thing you need to know is what domain you are going to use for your mail server. I strongly recommend mail.your-domain.com as it looks like a proper name for an email server, not something like ip-87-45.isp.com which will most likely end up in the spam folder. You will probably not be able to change the PTR record (known as reverse DNS) yourself, so contact your server provider to change the PTR record of your server's IP address to mail.your-domain.com.

2. A and CNAME records

    mail.your-domain.com A → 1.2.3.4 (your ip)

   for some clients you can optionaly setup:

   • smtp.your-domain.com CNAME mail.your-domain.com
   • pop.your-domain.com CNAME mail.your-domain.com
   • imap.your-domain.com CNAME mail.your-domain.com

Refresh the DNS diagnostics page and all checks should be green. However, poste.io will still not be able to receive and send emails properly - we need to set up the delivery domain as well.

Domain DNS

After installing the mail server, the default domain will be installed. Go to Virtual domains → your-domain.com [Show]

1. MX for your domain

   your-domain.com MX mail.your-domain.com

2. DKIM key

   Clicking on [create a new key] will instantly generate new key dedicated for your domain. All outgoing mail will now be signed with the DKIM key.

3. DNS DKIM, SPF, DMARC...

   Click on [DNS diagnostics]:

   • SPF record:

     your-domain.com. IN TXT "v=spf1 mx ~all"

     This literally means to pass all emails from the domain's mail server IP and soft-fail in other cases. An explanation of the options can be found at https://poste.io/spf?gmail.com

   • DKIM record (this is example only, copy one from your administration!):

     _s20160910378._domainkey.your-domain.com IN TXT "k=rsa;p=MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA0FvkMuwN46vvtQCC1JZz7XzRE+l+Lf8/5XUKwWJXOcE7dJoZBbOE0Gz85phZ2q+y4l8D7t/hXDz9q+6/KVQDgJ9muaxSM/uS+KG0ds0QLEiV0GYCVu+ZZQSNPBPjOwlDvo3LraW00lMpd5dUj+xpr07ShfIoULhi7/7t76n5GZMse9yBa4hIhxSG/wCAB4D6IWYBURz9Pc75IDPDTlImr3TP/82YrsULY70CHaPHA1+j1VPA5lE+tnmeqxJW6P537xSutDppv8BZg4nlF3ojg2k6LB/cq15C4QRPAMs77pRA4GVnys1LEJ3JDvV3/csOCZ49oC4m44/TnWXk057OAwIDAQAB"

     Public part of DKIM. You must set the selector (subdomain part) and TXT record exactly the same or it will not work.

   • DMARC record:

     _dmarc.our-domain.com. IN TXT "v=DMARC1; p=none; rua=mailto:dmarc-reports@our-domain.com"

     DMARC is not required, but it is a very helpful method of identifying delivery issues. An explanation of DMARC options can be found at https://poste.io/dmarc?gmail.com

   • autoconfig records are not required, but help some clients with initial configuration

If all the checks are green now, your mail server is ready to receive and deliver your emails! Now go and create your personal mailbox.