[Exim] external mail is not delivered anymore

Hello,

This is kinda of an emergency; I don't understand what's going on.
I'm currently searching the FAQ and list archives, and am posting this
message in case someone can help me faster. Please don't tell me to RTFM : I
am.
But my knowledge is poor in this area that's why I'm looking for help here
too.

anyway here it is :
I'm using Exim on a debian potato release.
A few days ago I upgraded from exim 3.12 to 3.22 by just installing the new
release over the old one.
Now mail headers show (Exim 3.22 #3 (Debian)) instead of (Exim 3.12 #1
(Debian)) so I guess the upgarde worked.
The exim.conf file has not been changed.

Ever since that upgrade, I have noticed external mails are not being
delivered to mailboxes !
Internal mails are delivered fine (I call internal mails those sent by cron
or using the mail command on the server).
External mails sent to domains hosted on my server just appear in the
mainlog but are not delivered.

for exemple :

2001-05-05 06:02:15 14vzsp-0008GJ-00 <= fel-x@??? H=mail.ifrance.com
[212.73.208.235] P=esmtp S=4348 id=13546.....5fc3@pc

is all that appears in the log when I send a mail to one of my accounts on
the server.
this stays as is in the log and is not processed. All I can do is type :

exim -d 5 -M 14vzsp-0008GJ-00

so I get exim to process the mail, check recipients and deliver it to the
right mailbox. Then only it adds the usual to the mainlog file :

2001-05-05 06:25:10 14vzsp-0008GJ-00 => fel-x <fel-x@???>
D=localuser T=local_delivery
2001-05-05 06:25:10 14vzsp-0008GJ-00 Completed

I am not willing to do this manually for every mail, that would just be
crazy.
What is going on ? why did exim stop processing and completing mail delivery
??

TIA for any help or suggestion,

Best regards.
FEL-X

--------------------------------
Dr Felix Shumelinsky
Ortho. Surgery Dept. - ULB
Free University of Brussels
Phone: +32 (0)495 51.67.42