# Smart_host



## fuhdan (Jan 8, 2013)

Hi all
I have the following issue:
In the configuration I have defined a smart host for outgoing emails

```
dnl Dialup users should uncomment and define this appropriately
define(`SMART_HOST', `smtp2go.com')dnl
```
But then I find in the logs:
delay=00:00:28, xdelay=00:00:02, mailer=relay, pri=121423, relay=treshna.com. [210.48.71.196], dsn=5.0.0, stat=Service unavailable

If I add the IP of the host smtp2go.com like:

```
dnl Dialup users should uncomment and define this appropriately
define(`SMART_HOST', `[207.58.142.213]')dnl
```
then I can see in the logs:
delay=00:04:30, xdelay=00:00:02, mailer=relay, pri=120033, relay=[207.58.142.213] [207.58.142.213], dsn=2.0.0, stat=Sent

The nslookup is working:
	
	



```
nslookup smtp2go.com
Server:		xxx.xxx.xxx.xxx
Address:	xxx.xxx.xxx.xxx#53

Non-authoritative answer:
Name:	smtp2go.com
Address: 207.58.142.213
```
Also the reverse lookup:

```
nslookup 207.58.142.213
Server:		xxx.xxx.xxx.xxx
Address:	xxx.xxx.xxx.xxx#53

Non-authoritative answer:
213.142.58.207.in-addr.arpa	name = smtp2go.com.

Authoritative answers can be found from:
```
Btw. In the mailertable I have configured also an esmtp host for a specific domain. And there the nslookup is working. And the string "treshna.com" I can't find in any sendmail config file. I don't know this domain.

I use the following system

```
FreeBSD hostname 9.1-RELEASE FreeBSD 9.1-RELEASE #0 r243825: Tue Dec  4 09:23:10 UTC 2012     [email]root@farrell.cse.buffalo.edu[/email]:/usr/obj/usr/src/sys/GENERIC  amd64
```

I use sendmail version: Version 8.14.5

What's wrong with my config? Or is this a known issue?
Thanks for any help.
Daniel


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## quintessence (Jan 16, 2013)

Hello,


```
;; ANSWER SECTION:
smtp2go.com.            26      IN      MX      10 treshna.com.
```

Sendmail found that MX record for the domain smtp2go.com is treshna.com.

EDIT:

If you would like to skip the MX lookup and to use smtp2go.com instead of treshna.com, you should place the hostname in square brackets (as you did with an IP address).
I'm using submit.cf for example:


```
# "Smart" relay host (may be null)
DS smtp2go.com
```
Sendmail will do MX lookup for the domain smtp2go.com, then will relay all your emails to hostname in the MX record, i.e. treshna.com


```
# "Smart" relay host (may be null)
DS [smtp2go.com]
```
Sendmail will not do MX lookup for the domain smtp2go.com, and will relay all your emails to the specified hostname, i.e. smtp2go.com.


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## fuhdan (Jan 19, 2013)

*Solved: Smart_host*



			
				quintessence said:
			
		

> Hello,
> 
> 
> ```
> ...



Thank you very much. That was it. now it works like a charm


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