Full upgrade would mean converting to use News::Article which uses PGP::Sign which uses gpg rather than pgp. That would probably be the right long term solution but is a moderately large piece of work. One benefit of that approach is that other features of News::Article could probably be used to replace a lot of formail calls and some other things too.

There are compatibility scripts to replace pmapp and pmcheck that also use gpg. Switching to those is a smaller change.

For now, I have a simple change (fix-pgpmoose branch) that can be used with the pgpgpg package which is available at least for Ubuntu and some configuration on systems with gpg but not pgp but which should still work with pgp (which I cannot test because I do not have it).

A decision is needed on whether or not to abandon pgp and switch to requiring gpg. If so, the compatibility scripts are a simple short term fix with converting to News::Article a possible longer term approach.