Writing a sympathy note to a business associate, client or customer is a bit more formal. You definitely want to avoid cards with any sort of religious connotations. Stick to cards with pictures of flowers, or landscapes or whatever, rather than something with a cross or other religious symbol, unless of course you happen to know that the family is very devout in their faith, and you share the same religious beliefs and faith.
Obviously, if your business is part of a devout religious community, and all of your customers, clients and business associates are all from the same faith, then it’s perfectly acceptable to send sympathy cards reflecting that faith. For everyone else, though, it’s best not to risk offending someone through the use of strong religious context that may not be part of their particular beliefs.
While it’s perfectly acceptable to have a company logo or imprint on your sympathy card to a client or business associate, make sure you still add a personal note and sign it yourself. This will let your client know that you consider them a friend, and go a long way toward building a good relationship with them. The note could go something like:
I’m so sorry for your loss. My wife and I really enjoyed meeting Sarah at the company Christmas party. She was such a gracious lady. Please let us know if there’s anything we can do for you.
While this last part may seem to go against the idea of not telling someone to call you unless they might really want to, it’s really meant in more of a business connotation. As a business colleague, you may be able to help them with any sort of work-related tasks that they feel too overwhelmed to handle.