Due to ongoing unresolved issues with the Delicious APIs, especially the constant "error saving link" errors, I have decided to discontinue Delicious Post.
The Mozilla Add-ons page for Delicious Post has been deactivated, and the Delicious Post page on the AE Creations website has been taken down. Downloads are no longer available; however, the Delicious Post forum will remain active.
If you already have Delicious Post installed, you can continue to use it (and put up with the ongoing errors originating from the Delicious Post API), but because development of Delicious Post has ended, no new features or bug fixes will be available.
Delicious Post is confirmed to be functioning with multi-process browser tabs (a.k.a. Electrolysis or e10s) -- for now.
Current users should consider looking at alternatives, such as the Delicious bookmarklet that is available from their website.
Delicious Post has been one of my favourite add-ons to work on. Years ago, I had forked the original "post to del.icio.us" add-on which was no longer maintained, and added a few features to make it better while maintaining its lightweight simplicity. I'm a Delicious user myself, so I counted myself as one of its avid users. It's regrettable that it has come to this, but having struggled with poorly-documented third party APIs that are outside my control and for which there are no known workarounds to its issues, I felt that this was the best course of action.
Thanks to all of its users, past and present, for their support.