What type of mail service is typically used for time-sensitive documents that do not require immediate attention?

First-class mail is the appropriate choice for time-sensitive documents that do not necessitate immediate attention. This service is designed for both letters and packages that require faster delivery than standard mail but do not need the expedited service offered by options like priority or overnight mail. First-class mail is typically delivered within 1 to 3 business days, making it a reliable option for important communications, such as billing statements, personal correspondence, and time-sensitive documents.

In contrast, priority mail is a higher level of service that offers quicker delivery, typically within 1 to 3 business days, and includes additional benefits such as tracking and limited insurance. This service may be used for more urgent communication. Overnight mail is specifically for documents that need to arrive the very next day, reflecting a sense of urgency. Standard mail, on the other hand, is the slowest and is best suited for non-urgent communications, with delivery times varying significantly.

Given these distinctions, first-class mail balances a reasonable speed of delivery with the nature of time sensitivity that does not require the urgency of overnight or priority options.