A surprise baby shower was thrown for me today at work

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There were a bunch of gifts, and one card with everyone's name on it. There were some names on the card, but those people weren't at the shower. Should I write individual thank you notes to everyone who signed the card? Should I just email thank you notes instead of getting everyone's address, or hand deliver them? (I've always gotten email thank yous from work showers... not sure what's protocol anymore)