Please stop replying to digests. If you must read the list via a digest, use a client that can reply to individual messages rather than the digest itself. Both Evolution and Thunderbird are perfectly capable of doing this. When you reply to a digest, not only does it change the Subject line to something completely meaningless, it also screws up standards-compliant message threading. The cosmetic problem can be fixed if you remember to do it. The threading problem cannot.
poc