[DATE, ex. Monday, March 31, 2008]

[NAME, COMPANY AND ADDRESS, ex.
Link Building
XYZ Inc.
1234 First Street
Suite 567
Anycity, Anystate  85245]

Dear [NAME, ex. Link Building],

You can understand my embarrassment when I was informed that my check to you (#[CHECK NUMBER]) was returned due to insufficient funds.  That is why I have immediately issued to you this letter and replacement check (#[CHECK NUMBER]), which is enclosed.

Please accept my apologies and assurance that this will not recur.

Sincerely,

[YOUR NAME, ex. Jill Jones]