Shareaza

That's just wrong. Seeding is started automatically by default upon a torrent's completion.

Glad to hear it. Shareaza also starts seeding as soon as it's downloaded a complete piece, right?

In any case, I will negotiate the case with one tracker that I frequent.
They seem to be reasonable. It may be they don't remember why they decided to block Shareaza years ago. And it looks like significant work has been done on BT in Shareaza over the years too.

I noticed that Shareaza changeset 9253 recently added an option to configure the identifying lead-in of the BitTorrent PeerID, evidently in order to masquerade as another client. The tracker I use elaborated somewhere on their forums or site about some various client features and behavior that cause problems for them or that they don't support, and I think this feature was among them. If the feature is exposed prominently, it might bother some tracker admins, but if the feature is well under the hood, I suspect it would not be an issue.

I don't really know how common it is for trackers to block Shareaza, but I understand this is not an isolated tracker in that regard... so maybe I can help change things there. The discussion might draw added interest in Shareaza itself, too.

As each normal BT client Shareaza already starts seeding before the torrent has finished downloading completely.

We'd be happy if you could negotiate with the tracker admin. If you need any further information, we'll provide you with it.

Custom PeerID was added against some strange tracker admins blocking EVERY client except white-listed ones for example uTorrent only. Anyway PeerID option is not easy accessible. Shareaza is a swiss-knife and it must download files from EVERYWHERE!