I find that is the best way to start a conversation. If you get on a mailing list and you are like ‘hey I want to add feature X’ the maintainer is probably going to be like: ‘ Oh fuck, I am so busy, go away, I hate feature X’. But if you come to them and you are like ‘I want to add feature X. I was thinking something like the attached patch’ which is totally wrong but you say, ‘But I think its totally wrong. I am thinking the right way might be to do X’ which is some more complex way, generally they will be like ‘Holly crap, they tried and look, they totally did it the wrong way. Maybe that pains the maintainer. They are like ‘ Oh man, I can’t believe they went through all that effort to do it. Its so easy to do the right thing,’ and then they reply.
This is the secret to being productive when contributing to open source. It’s very rare that you should approach a mailing list without a patch of some kind.