LiDIA's statement of GPL only in mailing list archives

["Jordi Gutierrez Hermoso" <jordigh@gmail.com>]

LiDIA is an excellent C++ library for computational number theory. A
few years ago, it had the best elliptic curve algorithms available
anywhere, but it's since been almost abandoned upstream:

    http://www.cdc.informatik.tu-darmstadt.de/TI/LiDIA/

Its authors have already agreed to release it under the GPL:

         http://www.cdc.informatik.tu-darmstadt.de/pipermail/lidia/2006-October/001117.html

However, they haven't actually indicated this in any form in LiDIA's
source tree. When pressed, they responded that the mention of GPL
license in the mailing list should suffice:

    http://www.cdc.informatik.tu-darmstadt.de/pipermail/lidia/2007-April/001150.html

Is this good enough for Debian? A mailing list announcement that all
of LiDIA's source tree is available under the GPL?

Thanks,
- Jordi G. H.