Starting yesterday June 15th Golden Star Ferries will start service to the Sporades islands of Skopelos, Skiathos and Alonissos from Thessaloniki.
I got this news from Shipping news sources and a contact on Alonissos.
However when I went to the Golden Star Web Site it had not been updated (no surprise) BUT at least one ticket consolidator/reseller Lets Ferry Greece did have the new route in their system.
This will make it much easier than departing from Volos if you are coming into Greece at Thessaloniki. The fare is reported to be 60 Euros p/p one way 108 return. The ferry will depart Thessaloniki at 10 am.
I hope this is helpful to others like myself that are trying to get to the Sporades from Thessaloniki.