Issues on email delivery

Hello, there is a problem when using sendmail to certain destinations, basically the recipient will reject the incoming message because the user@local.domain.com is used as the sender (Return-Path), they would verify local.domain.com is not a valid DNS record which is true because it is a local machine.

However the "From:" field in the custom header contains a valid address and host in DNS, let's say popeye@spinach.com.

Why does sendmail use @local.domain.com instead of using @spinach.com? I have a feeling this is solely down to the Return-Path because when I used the command "sendmail -t < header.txt -f popeye@spinach.com" it was received fine but that is abit of a hack fix.

I then tried setting "Return-Path: popeye@spinach.com" in the custom header.txt but it seemed to be keep overriding to user@local.domain.com again. So I proceeded to the look inside sendmail.cf, changed the Return-Path setting:
From:-

H?P?Return-Path: <$g>

To:-

H?P?Return-Path: <$f>

Refreshed sendmail, and triggered another message... however this made no difference it seems.

The recipient receives this message in the logs when rejecting:

Here is what we get in our logs, I highlighted the important part:

Thanks for any help you can provide.

Additionally, adding the server address to public DNS is not going to happen for security reasons.

The answer is having sendmail deliver the message with the sender as @spinnach.com (perferably the same as the From: ), instead of the machine address user@local.

if postfix is an option for you, I wrote this tutorial:
http://tech.gate.io/blogpost34

your problem is the "from" field

if you want, I have a sendmail solution too which I can post tomorrow
this one has the advantage, that "from" field is rewritten to

From: hostname <username@domainyoulike.com>

for AIX, you have to run "newaliases" after postfix the installation, then it'll work fine

I'm not sure that the problem is the "From:" field because it is showing the correct address? I don't think I would be allowed to install postfix....

shoudn't it be

from=<user@ourdomain.com
instead of
from=<user@local.ourdomain.com
?

Yeah... now I'm confused because it shows the correct From: address when it is sent to me (I'm CCing myself).

The sendmail.cf is showing $g's, perhaps changing the $g to $f might help... or maybe I'm going into the totally wrong direction.
H?F?From: $?x$x <$g>$|$g$.

in the mc file:

FEATURE(masquerade_entire_domain)
FEATURE(masquerade_envelope)
MASQUERADE_AS(`external.domain')
MASQUERADE_DOMAIN(`hostname.domain.local')

in the sendmail.cf file, comment

#CL root
#C{E}root

so that the masquerading works for root too

Thanks for the reply, but what would that do? Is there any disadvantages to using masquerading? Would it be bad if there is no sendmail.mc file?

you don't really need the mc file, sendmail make generates the cf file from the mc file

you could try to add these lines manually to sendmail.cf

#CL root
#C{E}root
C{w}localhost.localdomain
C{M}local.ourdomain.com 
# who I masquerade as (null for no masquerading) (see also $=M)
DMourdomain.com 

but editing the cf file manually may not work when doing big changes like that

I have not tried this yet but I will do, just need to get access to the sendmail.cf (it is restricted to certain privileges). I take it there is no way to get the sender address the same as what is set for the "From:" field?

Is there a way to masquerade on specific ID's instead of all outgoing mail?

this can be done with a genericstable

FEATURE(generics_entire_domain)
FEATURE(genericstable, `hash -o /etc/mail/genericstable')
GENERICS_DOMAIN(`hostname.domain.local')

with this method, you can specify any emailsubstitution

an entry can look like:

apache appuser@external.domain

makemap -v hash genericstable < genericstable 

but you don't have the mc file, so probably you have to install additional sendmail packages, I can't tell you how the final .cf file looks like with this changes