Kluu is quite right; on MFC 1.3 there are as many folders in the incoming directory as your configured hosts, named "1" "2" "3" and so on.
If you drop in there the mail log files with an extension ".s.001.r", they are processed by MFC at its next restart; I don't know it it works even without renaming the log files If your MFC is not configured at all, that is you have no host defined and no folder under "incoming", simply create as many hosts as you need in MFC and then create the # folders.
Hope this works on MFC 1.4 too.

Thank you.
I found the directory:

MailFlowCentral\Mail Flow Central\mailFC\mgaLogs\incoming

I tried the following steps:

a) I copy some files from the offline-log-directory "mail_logs" looking like mail.@20070313T114112.s
b) I stopped and started the service "Mail Flow Central"
-> No luck:

There is currently no data in the Mail Flow Central database. 

c) I renamed the above files to mail.@20070313T114112.s.001.r and repeated b).
-> No luck:

There is currently no data in the Mail Flow Central database. 

d) I moved the above files to the manually created \1\ and repeated b).
-> No luck:

There is currently no data in the Mail Flow Central database. 

e) I renamed back the above files to mail.@20070313T114112.s still in \1\ and repeated b).
-> No luck:

There is currently no data in the Mail Flow Central database. 

Could you please have a look what I need else for my installed MFC-version 1.4.0-103?

In the meantime, I have added a "dummy-host" with the IP "localhost" and the logname "mail*".
Seconds after I put some of the above files (with or without the extension .001.r) the files are processed and moved to

MailFlowCentral\Mail Flow Central\mailFC\mgaLogs\archive\1

Unfortunately, the results remain the same:

There is currently no data in the Mail Flow Central database. 

But in the host-section I found this error:

Mon, 21 Apr 2008 18:10:54 +0100  Failed  Unsuccessful import. Error while importing file. Import failed, an error occurred with the downloaded log file: '[Errno 13] Permission denied: '.\\mgaLogs\\incoming\\1\\mail.@20070313T114112.s.001.r''  

What kind of permission should I set (I'm trying it actually on my WinXP without any permission set on this MFC-Directories..)

Nobody has such a configuration?

The most simple solution i can think of is run a small FTP server on that system to serve the logfiles. Then point MFC to localhost and let it fetch the logs from there.

I'm actually doing something similar like that. My MFC has no access to the Ironports or the other way around. The ironports push their logs to an FTP server, and MFC pulls the logs from that server. Never had a problem with that setup, just have to point MFC to the correct host/directory.

Good idea! I try to do that with a small "portable" FTP-Server.