Pkg exim4 users - Mar 2005 - After upgrading to exim4 messages are frozen, "remote host address is the local host"

Hi,

I''m running Debian unstable, and I decided I wanted to upgrade to
exim4.
  When I did so, I found that all mail, both from on the host itself and 
from the wider internet, wasn''t being delivered any more.  A typical 
message (this one happened to be a test mail I sent to myself on the 
server machine itself) produces this log file:

2005-03-07 11:00:05 Received from <username>@exon.dyndns.org 
U=<username> P=local S=335
2005-03-07 11:00:05 <username>@exon.dyndns.org R=dnslookup defer (-1): 
remote host address is the local host
*** Frozen

When I asked about this on the exim support list, I was told that I must 
have misconfigured my machine''s local mail domains.  I don''t
really
understand that, but it sounds like the debconf question that asked me 
which domains should be considered local.  I entered "exon.dyndns.org"
and another host, "aeon.exon.dyndns.org", as local domains, so that 
sounds right to me.  I''m at a loss what else I''ve done wrong.

However, this talk of DNS lookups does remind me that there''s weird 
behaviour on my machine, in that all invalid domains seem to resolve to 
my own machine:

charly:~# ping blah.org
PING exon.dyndns.org (82.135.65.152): 56 data bytes
64 bytes from 82.135.65.152: icmp_seq=0 ttl=64 time=0.9 ms

I''ve never understood why that happens, or even been sure it
wasn''t a
"feature".  So possibly it''s the DNS or IP masquerading
systems that are
at fault.  But still, at least local mail delivery should be immune to 
that, right?

I don''t really want to be playing with all this stuff - I''m
just trying
to work around bugs in Thunderbird.  Thunderbird doesn''t play nicely 
with mbox servers - you can''t create folders with subfolders if you
ever
want to delete them again later.  And mbox doesn''t support folders
which
contain both messages and subfolders.

So I''m trying to migrate to maildir.  But that doesn''t seem to
be
trivial under Debian, and if I''m going to get any support from the exim
mailing list, I''m told I need to be on exim4.  Hence the upgrade.

I just went a day without receiving any email, which I''ve fixed by 
reverting to exim 3.  I don''t really want to try the upgrade again 
unless I''m sure it''s going to work...

Any advice?

Thanks,
Matthew Exon

Hi Matthew,

On Mon, Mar 07, 2005 at 02:53:11PM +0100, Matthew Exon
wrote:
> I''m running Debian unstable, and I decided I wanted to upgrade to
exim4.
>  When I did so, I found that all mail, both from on the host itself and 
> from the wider internet, wasn''t being delivered any more.  A
typical
> message (this one happened to be a test mail I sent to myself on the 
> server machine itself) produces this log file:
> 
> 2005-03-07 11:00:05 Received from <username>@exon.dyndns.org 
> U=<username> P=local S=335
> 2005-03-07 11:00:05 <username>@exon.dyndns.org R=dnslookup defer
(-1):
> remote host address is the local host
> *** Frozen
> 
> When I asked about this on the exim support list, I was told that I must 
> have misconfigured my machine''s local mail domains.  I
don''t really
> understand that, but it sounds like the debconf question that asked me 
> which domains should be considered local.  I entered
"exon.dyndns.org"
> and another host, "aeon.exon.dyndns.org", as local domains, so
that
> sounds right to me.  I''m at a loss what else I''ve done
wrong.
What does "exim -d -bt <username>@exon.dyndns.org" say?

> However, this talk of DNS lookups does remind me that there''s
weird
> behaviour on my machine, in that all invalid domains seem to resolve to 
> my own machine:
> 
> charly:~# ping blah.org
> PING exon.dyndns.org (82.135.65.152): 56 data bytes
> 64 bytes from 82.135.65.152: icmp_seq=0 ttl=64 time=0.9 ms
> 
> I''ve never understood why that happens, or even been sure it
wasn''t a
> "feature".  So possibly it''s the DNS or IP masquerading
systems that are
> at fault.
That sounds odd.
> So I''m trying to migrate to maildir.  But that doesn''t
seem to be
> trivial under Debian, and if I''m going to get any support from the
exim
> mailing list, I''m told I need to be on exim4.  Hence the upgrade.
It is quite easy to do with exim 3 if one knows a little bit about
exim configuration. And it is even easier do to with exim 4, because
it is documented how to do this in
/usr/share/doc/exim4-base/README.Debian.gz

Greetings
Marc

-- 
-----------------------------------------------------------------------------
Marc Haber         | "I don''t trust Computers. They | Mailadresse
im Header
Mannheim, Germany  |  lose things."    Winona Ryder | Fon: *49 621 72739834
Nordisch by Nature |  How to make an American Quilt | Fax: *49 621 72739835

OK, I figured out what my problem was.  I didn''t read the entire dialog
box carefully enough and missed that the list of local domains had to be 
colon separated.  I entered them space separated.  As a result, exim 
believed that it should only be handling mail for the domain 
"exon.dyndns.org<space>aeon.exon.dyndns.org", and rejected any
email
merely destined for exon.dyndns.org.

I wasn''t paying close enough attention to the specification, because I 
was having trouble with figuring out what my answer should be: I''m on
an
IP masqueraded local network.  I have a dyndns.org domain, which means 
that *.exon.dyndns.org, as well as plain exon.dyndns.org, all gets 
routed to my own box.  Internally, my machines are called 
<blah>.exon.dyndns.org.  So where should email to aeon.exon.dyndns.org 
go?  Forwarded to aeon, or stay on my server?  Is anything going to 
break?  In all that, I forgot to concentrate on the syntax I was 
supposed to be using.

So I''m an idiot, sure, but this all seems a little fragile for such a 
tiny mistake.

It seems like the first check that should be made, when a user enters a 
list of domains, is that each of the domains should be looked up to see 
if they really exist.  If not, the user should be warned.  Ideally this 
would be handled by debconf.

Again, ideally, exim would also perform this check when it starts up, 
and figure out some way to warn postmaster if there''s a problem.

Simply quietly refusing to send any email when the user makes this 
mistake seems a trifle mean :-(

Marc Haber wrote:
> What does "exim -d -bt <username>@exon.dyndns.org" say?
(In case you hadn''t guessed, I''m replacing the username to
avoid having
a harvestable email address online...)

For Exim 3:

Exim version 3.36 debug level 1 uid=0 gid=0
Berkeley DB: Sleepycat Software: Berkeley DB 3.2.9: (May 26, 2004)
<username>@exon.dyndns.org
   deliver to <username> in domain exon.dyndns.org
   director = localuser, transport = local_delivery

For Exim 4, incorrectly configured:

Exim version 4.44 uid=0 gid=0 pid=25603 D=fbb95cfd
Berkeley DB: Sleepycat Software: Berkeley DB 4.2.52: (December  3, 2003)
Support for: iconv() IPv6 GnuTLS
Lookups: lsearch wildlsearch nwildlsearch iplsearch cdb dbm dbmnz 
dsearch nis nis0 passwd
Authenticators: cram_md5 plaintext
Routers: accept dnslookup ipliteral manualroute queryprogram redirect
Transports: appendfile/maildir/mailstore autoreply lmtp pipe smtp
Fixed never_users: 0
changed uid/gid: forcing real = effective
   uid=0 gid=0 pid=25603
   auxiliary group list: <none>
configuration file is /var/lib/exim4/config.autogenerated
log selectors = 00000ffc 00010400
trusted user
admin user
user name "root" extracted from gecos field "root"
originator: uid=0 gid=0 login=root name=root
sender address = <root user>@exon.dyndns.org
Address testing: uid=0 gid=102 euid=0 egid=102
 >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
Testing <username>@exon.dyndns.org
 >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
Considering <username>@exon.dyndns.org
 >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
routing <username>@exon.dyndns.org
--------> hubbed_hosts router <--------
local_part=<username> domain=exon.dyndns.org
checking domains
expansion of "${if 
exists{/etc/exim4/hubbed_hosts}{partial-lsearch;/etc/exim4/hubbed_hosts}fail}"
forced failure: assume not in this list
hubbed_hosts router skipped: domains mismatch
--------> dnslookup_relay_to_domains router <--------
local_part=<username> domain=exon.dyndns.org
checking domains
exon.dyndns.org in "@:localhost:exon.dyndns.org aeon.exon.dyndns.org"?
no (end of list)
exon.dyndns.org in ""? no (end of list)
exon.dyndns.org in "! +local_domains : +relay_to_domains"? no (end of
list)
dnslookup_relay_to_domains router skipped: domains mismatch
--------> dnslookup router <--------
local_part=<username> domain=exon.dyndns.org
checking domains
cached no match for +local_domains
cached lookup data = NULL
exon.dyndns.org in "! +local_domains"? yes (end of list)
R: dnslookup for <username>@exon.dyndns.org
calling dnslookup router
dnslookup router called for <username>@exon.dyndns.org
   domain = exon.dyndns.org
DNS lookup of exon.dyndns.org (MX) gave NO_DATA
returning DNS_NODATA
DNS lookup of exon.dyndns.org (AAAA) gave NO_DATA
returning DNS_NODATA
DNS lookup of exon.dyndns.org (A) succeeded
82.135.65.152 in "0.0.0.0 : 127.0.0.0/8 : 192.168.0.0/16 :172.16.0.0/12 
: 10.0.0.0/8 : 169.254.0.0/16"? no (end of list)
local host found for non-MX address
fully qualified name = exon.dyndns.org
exon.dyndns.org 82.135.65.152 mx=-1 sort=-458
LOG: MAIN
   remote host address is the local host: exon.dyndns.org (while routing 
<<username>@exon.dyndns.org>)
dnslookup router: defer for <username>@exon.dyndns.org
   message: remote host address is the local host
search_tidyup called
 >>>>>>>>>>>>>>>> Exim pid=25603
terminating with rc=1
>>>>>>>>>>>>>>>>
<username>@exon.dyndns.org cannot be resolved at this time:
   remote host address is the local host

For Exim 4, correctly configured: too much to attach.  Suffice to say, 
it works :-)

On Mon, Mar 07, 2005 at 03:41:05PM +0100, Matthew Exon
wrote:
> OK, I figured out what my problem was.  I didn''t read the entire
dialog
> box carefully enough and missed that the list of local domains had to be 
> colon separated.  I entered them space separated.  As a result, exim 
> believed that it should only be handling mail for the domain 
> "exon.dyndns.org<space>aeon.exon.dyndns.org", and rejected
any email
> merely destined for exon.dyndns.org.
I see. Great that you found the issue.
> It seems like the first check that should be made, when a user enters a 
> list of domains, is that each of the domains should be looked up to see 
> if they really exist.  If not, the user should be warned.  Ideally this 
> would be handled by debconf.
Well, maybe you are preparing your mail server to accept e-mail for a
domain that has not yet been put into service. This is normal way of
operation for bigger sites.
> Again, ideally, exim would also perform this check when it starts up, 
> and figure out some way to warn postmaster if there''s a problem.
I would put these checks in the update-exim4.conf script which is
invoked right before exim4 starts up. This is the logical way to do
it, at the price of not being able to use Debconf for the warning.

otoh, I do not think that it is possible with reasonable effort to do
tests that will catch most possible errors. As I outlined above, there
might be justification for using a domain that does not yet exist in a
domain list. It would be reasonably easy to check whether a domain
list is correctly separated with colons, avoiding your mistake, but
there are gazillions of other possibilities to break a setup. I
believe it is impossible to catch all of them. So adding a check for
this mistake is like opening a can of worms which I would really like
to avoid.
> For Exim 4, correctly configured: too much to attach.  Suffice to say, 
> it works :-)
Fine ;)

Greetings
Marc

-- 
-----------------------------------------------------------------------------
Marc Haber         | "I don''t trust Computers. They | Mailadresse
im Header
Mannheim, Germany  |  lose things."    Winona Ryder | Fon: *49 621 72739834
Nordisch by Nature |  How to make an American Quilt | Fax: *49 621 72739835

Marc Haber wrote:
>>So I''m trying to migrate to maildir.  But that doesn''t
seem to be
>>trivial under Debian, and if I''m going to get any support from
the exim
>>mailing list, I''m told I need to be on exim4.  Hence the
upgrade.
> 
> 
> It is quite easy to do with exim 3 if one knows a little bit about
> exim configuration. And it is even easier do to with exim 4, because
> it is documented how to do this in
> /usr/share/doc/exim4-base/README.Debian.gz
It is indeed very easy to do with exim 4, and I now have a full folder 
system working!  Thanks very much for your help!

Mat

On Mon, Mar 07, 2005 at 06:18:33PM +0100, Matthew Exon
wrote:
> Marc Haber wrote:
> >>So I''m trying to migrate to maildir.  But that
doesn''t seem to be
> >>trivial under Debian, and if I''m going to get any support
from the exim
> >>mailing list, I''m told I need to be on exim4.  Hence the
upgrade.
> >
> >
> >It is quite easy to do with exim 3 if one knows a little bit about
> >exim configuration. And it is even easier do to with exim 4, because
> >it is documented how to do this in
> >/usr/share/doc/exim4-base/README.Debian.gz
> 
> It is indeed very easy to do with exim 4, and I now have a full folder 
> system working!  Thanks very much for your help!
You''re welcome.

Greetings
Marc

-- 
-----------------------------------------------------------------------------
Marc Haber         | "I don''t trust Computers. They | Mailadresse
im Header
Mannheim, Germany  |  lose things."    Winona Ryder | Fon: *49 621 72739834
Nordisch by Nature |  How to make an American Quilt | Fax: *49 621 72739835