速達

1. Origins, structure, and basic meaning

• Structure: 速達 (そくたつ) is the postal noun express mail or special delivery.
• Basic usage: 速達で送る marks the delivery method; 手紙を速達にする selects express handling for a letter.

2. Common pitfalls and similar expressions

• Method with で and choice with にする
  • で states the chosen means, whereas にする describes changing or assigning the mailing category.