Are thank-you notes expected for condolence cards?

Dear Polite One:

Do I need to write thank-you notes for condolence cards?  I will acknowledge those who sent flowers and paid Shiva calls.  

Sincerely,

Curious

Dear Curious,

Please accept my condolence on your loss.  It is expected to send thank-you notes out to those who send condolence letters, but not for off-the-rack cards.  

Sincerely,

The Polite One

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