DNS record for clients (facultative)

To help clients finding automatically how to configure parameters to use your mail server, you can add specific DNS records.

_submission._tcp.athome.tld  86400   IN  SRV 0 1 587 athome.tld
_imap._tcp.athome.tld        86400   IN  SRV 0 0 0   .
_imaps._tcp.athome.tld       86400   IN  SRV 0 1 993 athome.tld

Read rfc6186 about these records.