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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 square brackets but how do I designate the mailbox username for the (virtual) hosted account on the server?

In other words,

  • I have multiple domains hosted on a virtual server -- all sharing the same IP address
  • obviously, user@domain.com works fine
  • but how do I send to user@[123.456.78.90]

Is what I want to do, possible?

Thanks.

H. Ferrence
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  • I tried using the "hosts" file to specify an unused domain name for the desired IP address, and made email accounts for that domain name, but it didn't work. I am trying test a hosting site migration and getting too much interference from the old IP address if I simply rely on "hosts" to redirect the correct domain name. Has anyone else gotten anything like this working? – David Spector Sep 30 '19 at 13:09

2 Answers2

8

A virtual host needs a domain name in order to figure out what to do. You want to send it to an IP address instead of a domain name. Thus it is not going to work through normal methods. You might be able to specify a "default" domain if none match Otherwise, your only hope is to manually forge email. By this, I mean:

telnet 123.456.78.9 25
HELO myhostname.mydomain
MAIL From: <myemail@mydomain>
RCPT To: <user@domain.com>
DATA
From: myemail@mydomain
To: user@domain.com
Subject: Testing

This is a test
.
QUIT
Seth Robertson
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  • what about to fake domain name to an IP format? Domains are only used to allow multiple instances over same IP. I guess the real problem is not send it, the problem is the receiver will NOT accept your connection withoud a email. Some of them will not accept you based on rules/lists/test and some other, so remove hostname/domain will be a fast way to get out the system. – m3nda Dec 30 '14 at 07:53
2

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.

Stuart Gathman
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  • Ah, using sendmail from the command line doesn't handle raw ips - but SMTP works fine. If mutt is configured to run sendmail rather than use SMTP, that could be the problem. – Stuart Gathman Aug 31 '17 at 04:11