In my campaign (DnD 5e) I would like to send players on a quest to save a kidnapped person. The person has high value information. He/she was ambushed and taken prisoner.
My question is: is there a logical reason for sending a person to deliver a message instead of using 3rd level spell Sending? The spell has no range limitations, and message can be up to 25 words long. What are good reasons for not using a spell? The sender and the receiver would both have resources to hire a Wizard, Bard or Cleric to cast spell, so not using the spell option should be more complex than just “Caster is not available”. In addition the length of a message is less than 25 words.
I would like to keep the idea of sending party on a rescue mission, just need a logical reason for doing so.