Accept mail from any domain--don't check if domain is valid

[dpuryear]

We receive a lot of mail from internal servers at remote sites and their domain doesn't show up as valid (e.g., HOSTNAME.example.com is not valid via public DNS). Scalix, by default, appears to be rejecting that as mail_check in Sendmail (or so it seems).

How can I safely disable this check without breaking anything?

[ScalixSupport]

Are these remote sites trying to relay through your Scalix server or just send to a Scalix user? If it's the former, then you'll need to add "RELAY accept .example.com" to your /var/opt/scalix/sys/smtpd.cfg file then restart the SMTP Relay by typing:

omoff -d0 smtpd
omon smtpd

Thanks,
Rachel

[dpuryear]

Hi Rachel. They are just trying to send to local Scalix users. Basically, we have remote systems that want to send mail to server-mail@example.com, where I am 'example.com'. Most of these remote systems do not have valid public DNS names (they have names like SERVERX.organization.com, where SERVERX is only valid to organization.com's internal DNS).

Are these remote sites trying to relay through your Scalix server or just send to a Scalix user? If it's the former, then you'll need to add "RELAY accept .example.com" to your /var/opt/scalix/sys/smtpd.cfg file then restart the SMTP Relay by typing:

omoff -d0 smtpd
omon smtpd

Thanks,
Rachel

[hydrospace]

HI,

one quick hint: just add the ip adress and the domain name to you /etc/hosts file. Sendmail wil then accept these domains as valid ones...

Stefan

[ScalixSupport]

If you're filtering mail over to sendmail then you need to tweak sendmail to accept unresolvable domains. You can do that by editing your /etc/mail/sendmail.mc file and looking for this line:

Code: Select all

dnl #FEATURE(`accept_unresolvable_domains')dnl


and changing it to be:

Code: Select all

FEATURE(`accept_unresolvable_domains')dnl


then rebuild your sendmail.cf file from that. Be sure to save a copy of your original sendmail.cf file in case something goes wrong. You'll need to add back the Scalix changes to your sendmail.cf file by typing:

Code: Select all

omsendin


If you've added the spamassassin changes to your sendmail.cf file you'll need to add those back as well.

Thanks,
Rachel

[dpuryear]

I don't think that's it. First, I noticed that /etc/mail/sendmail.cf is already configured to allow unresolveable domains. Also, that sendmail only listens to 127.0.0.1:25. omsmtpd listens to public-ip:25:

[root@mail mail]# netstat -lntp | grep 25
tcp 0 0 0.0.0.0:5729 0.0.0.0:* LISTEN 2552/advmail.sckd
tcp 0 0 0.0.0.0:389 0.0.0.0:* LISTEN 2593/omslapd
tcp 0 0 0.0.0.0:143 0.0.0.0:* LISTEN 2581/in.imap41d
tcp 0 0 public-ip:25 0.0.0.0:* LISTEN 2179/omsmtpd
tcp 0 0 127.0.0.1:25 0.0.0.0:* LISTEN 2358/sendmail: acce

So shouldn't I be modifying omsmtpd instead?

I don't see how this is done in the docs.

[dpuryear]

Also, I tried that. I found that sendmail.mc already had that. Regardless, I did the following:

# m4 sendmail.mc > sendmail.cf
# omsendin
... Y

I let sendmail restart.

I still cannot accept unresolveable domains. I get "Domain of sender xyz does not exist."

[hydrospace]

Hi,

did you added your sending domain names in your /etc/hosts file? So the sendmail will try to resolve the domain by DNS and will receive a valid IP adress. No matter if it is a private one or not. It helped us with a problem @subdomain.domain.com did not existed in public dns. So we added the entry to the /etc(hosts file and it worked fine. I would not open the accept_unresolvable_domains"-switch...

Stefan

[dpuryear]

We could do that, but.. it would be hard. Really, we have so many servers sending us emails that we really need to just accept email from any sender. We still run our mail through SA, and that does a fine job of keeping us clean. We aren't all that worried about unresolveable domains.

At this point, I'm not sure that this can be done using Scalix. I found that Scalix uses it's SMTP Relay to accept mail from the Internet, not Sendmail. Unless I'm mistaken then, setting Sendmail to accept unresolveable domains won't help then since it's SMTP Relay that is kicking back the email. Is this correct?

[ScalixSupport]

Hi. The reason you need to tweak sendmail is because Scalix uses sendmail to do some of it's address verification routines. Can you post the actual bounced message that people are getting back? Sendmail has a few different errors and would be helpful for us to know which you're getting, is it a 4.1.8 451 Domain of sender address ..., a 5.1.8 553 Domain of sender address ... or something else.

Thanks,
Rachel

[dpuryear]

I had to edit submit.mc (instead of sendmail.mc). After a quick 'make submit.cf' it worked.

Thanks!

[tchen]

Can you tell me how did you change your submit.mc? I have very similar problem,
but I don't know if my submit.mc is set correctly, it went with default setting. Thanks a lot.

[Kris]

I have exactly the same problem..

So if I read correctly, I will need to change my submit.mc file, but I don't know what to change

Here is my current submit.mc:

Code: Select all

divert(0)dnl
include(`/usr/share/sendmail-cf/m4/cf.m4')
VERSIONID(`linux setup for Red Hat Linux')dnl
define(`confCF_VERSION', `Submit')dnl
define(`__OSTYPE__',`')dnl dirty hack to keep proto.m4 from complaining
define(`_USE_DECNET_SYNTAX_', `1')dnl support DECnet
define(`confTIME_ZONE', `USE_TZ')dnl
define(`confDONT_INIT_GROUPS', `True')dnl
define(`confPID_FILE', `/var/run/sm-client.pid')dnl
dnl define(`confDIRECT_SUBMISSION_MODIFIERS',`C')
FEATURE(`use_ct_file')dnl
dnl
dnl If you use IPv6 only, change [127.0.0.1] to [IPv6:::1]
FEATURE(`msp', `[127.0.0.1]')dnl