Problems with clearsign option

[cord-henning.fricke at f-i.de]

Hi Folks,

I'm new to this site and I have a prob with the gpg --clearsign option.
My mails to RIPE NCC are signed with my PGP-Key.
This worked well for the last 6 years. Now I have the prob, that the 
signature is called bad from the RIPE mailer

I' using:

gpg (GnuPG) 1.4.11 on ubuuntu
the email client is Lotus Notes 8.5

when I'm signing mails and veryfing them on the cmd:

~/.gnupg$ gpg --verify test.asc
gpg: Signature made Wed 19 Oct 2011 08:50:20 AM CEST using DSA key ID 
696F76DD
gpg: Good signature from "ASXXXX Maintainer <user at domain>"

everything works fine.

The same Mail sent over my Notesclient:


***Error: The following PGP credentials were not correct:
696F76DD

***Error: PGP signature validation failed:
gpg: Signature made Tue 18 Oct 2011 12:55:32 PM CEST using DSA key ID 
696F76DD
gpg: BAD signature from "ASXXXX Maintainer <user at domain>"



The interessting thing is, that it sometimes works!
Nothin done in another way all things are done the same way and it's ok.


I tried it on several systems with gpg 1.4.6 up to 1.4.11.
When I'm using the new environment the first mail is accepted the next 
mails are rejected - is there a caching mechanism enabled?
I can't find a solution or a way for a solution for this prob.

Any help would be appreciated

Thanks

Cord