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  • hostname in sender address

    From Nick Hocking@21:1/5 to All on Wed Aug 4 18:07:55 2021
    Sendmail, right out of the box, puts the sender address, in the headers and the "MAIL From:" address in the envelope , as (for example), "username@myhostname.mydomainname.com".

    I am being told that the use of "myhostname" in these addresses is incorrect and that the addresses should just be username@mydomainname.com"

    Is this correct?

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Claus =?iso-8859-1?Q?A=DFmann?= @21:1/5 to Nick Hocking on Thu Aug 5 05:35:06 2021
    Nick Hocking wrote:

    I am being told that the use of "myhostname" in these addresses is incorrect and that

    By whom and what was the explanation why it would be "incorrect"?

    the addresses should just be username@mydomainname.com"

    Is this correct?

    No.
    (well, actually yes: myhostname.mydomainname.com does not have an MX
    record, but mydomainname.com does -- is that your domain?)

    It depends on your (DNS) setup -- if HOST.DOMAIN.TLD has an MX
    record and your MTA accepts mail for it it is just fine.

    PS: see also cf/README: MASQUERADING

    --
    Note: please read the netiquette before posting. I will almost never
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    is too lazy to trim his article, and it's wasting the time of all readers.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Nick Hocking@21:1/5 to All on Wed Aug 4 23:27:58 2021
    On Thursday, August 5, 2021 at 3:40:01 PM UTC+10, Claus Aßmann wrote:
    Nick Hocking wrote:

    I am being told that the use of "myhostname" in these addresses is incorrect and that
    By whom and what was the explanation why it would be "incorrect"?
    the addresses should just be user...@mydomainname.com"

    Is this correct?
    No.
    (well, actually yes: myhostname.mydomainname.com does not have an MX
    record, but mydomainname.com does -- is that your domain?)

    It depends on your (DNS) setup -- if HOST.DOMAIN.TLD has an MX
    record and your MTA accepts mail for it it is just fine.

    PS: see also cf/README: MASQUERADING

    --
    Note: please read the netiquette before posting. I will almost never
    reply to top-postings which include a full copy of the previous
    article(s) at the end because it's annoying, shows that the poster
    is too lazy to trim his article, and it's wasting the time of all readers.

    Thanks Claus, yes this seems to be the problem. (no MX record)
    myhost.a.b.c.com.au has no MX record whereas domain a.b.c.com.au does.

    In the past this caused no issues since we had control of the DNS and SMTP for a.b.c.com.au and b.c.com.au and the many machines (of which myhost is one) never sent undeliverable e-mails :-)

    This situation dates back 20 years or so but now that we don't control the DNS for a.b (or b) I agree that we must either get all our hosts registered with MX records or use Masquerading.

    Still, since this is likely to be a short term issue anyway, maybe the best solution is to use the S1 ruleset to just strip off the hostname ($w) in the sender address and return path. ( I have tested this and it works as expected.)

    PS: my other question also relates to this. The other organisation seems to have made special exemption for one of our servers (say hostx.a.b.c.com.au) so I may be able to solve my problems (though not theirs) by getting all out hosts to smart host
    hostx.

    I'll test this out on my personal laptop with three centos vm's under virtualbox, just for interest, since I don't think that that would be a good workaround.

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