Sending Email using IP Address instead of Domain Name

Question

I am trying to avoid running through DNS servers to get an email message to an address on one of my hosted virtual accounts.

I know I can surround the IP address with sq

Answer 1

What you want to do is possible, and even secure when using Cjdns IPs. Some clients (e.g. mutt) are "broken" and choke on raw ips as domain. (While technically broken, it is an uncommon use case - mutt is a good client.)

You'll need to tell your MTA to accept the raw ip. E.g. on sendmail, add [123.456.78.9] to /etc/mail/local-host-names

You'll also have to turn on accept_unresolvable_domains as sendmail doesn't seem to regard already resolved domains as "resolvable". (Other MTAs may require different tweaks.)

I use thunderbird to send to raw ips, and it works just fine. A friend uses claws-mail with no problems.