A transmittal or cover letter accompanies a larger item, usually a document. The transmittal letter provides the recipient with a specific context in which to place the larger document and simultaneously gives the sender a permanent record of having sent the material.
Transmittal letters are usually brief. The first paragraph describes what is being sent and the purpose for sending it. A longer transmittal letter may summarize key elements of the proposal in one or two sentences and provide the recipient with other useful information.
End transmittal letters with a one-sentence paragraph that establishes goodwill by thanking or complimenting the recipient.
The following document is an example of a formal transmittal letter accompanying a grant proposal to the National Science Foundation. The structure of the letter, the use of language, such as herewith, and the use of the passive voice reflect common conventions for submitting formal scientific proposals.