Crusted Port is Vegan Friendly

Company email (February 2011):
"There are two styles of Port: Wood Aged and Bottle Aged. Wood Aged Ports when bottled are filtered with a fining agent not considered suitable for people choosing a vegan diet.

Bottled Aged Ports are bottled unfiltered and are therefore considered suitable for people choosing a vegan diet. Bottle Aged Ports are Vintage Port, Single Quinta Vintage Port and Traditional Late Bottled Vintage Ports.

Along similar lines just an FYI...
"Gluten Free - While some wines cannot be called Gluten Free because of the flour used to seal casks together.
We have confirmed with our winemakers that this is not true for our Ports. We are gluten free."

Company email (April 2009):
"I had to get the official answer from Symington Family Estates, owners of Dow's Ports. Here's what they said:
Bottle Matured Ports - Crusted, Traditional LBV, Single Quinta and Vintage are not fined and are therefore all suitable for Vegans.
Wood Ports and Douro DOC are not suitable for vegans.
Wood Ports are your Aged Tawny Ports, Reserve Port, Standard LBV, Standard Ports.
Let me know if you need further explanation. Also to be specific Dow's does not make a traditional LBV. Only Smith Woodhouse and Warre's make these from our family of brands."