Only in the event that you already know the recipient should you consider alternatives such as "Kind regards," or "With best wishes," appropriate. If in doubt, stick to "faithfully," or "sincerely,". Also note that in either case, the "Y" of "Yours" is capped, and the "f" or "s" of "faithfully," or "sincerely," respectively is lower_case. Note the comma after both "faithfully," and "sincerely," too. The positioning of the closing phrase differ depending on the format: FBF: Align left, MBF: Align right.
The language used in the sales letter format should be simple, and suited to your trade. Complicated or complex writing leaves the reader confused and unlikely to read your letter or take action and buy. When a letter writer includes any bonuses, they should be supported with the word "free." For example: "FREE article submission with every SEO article! "By following proper sales letter format, you can increase the number of people who will read and respond to your letter. The subject line must be motivating and the envelopes are to be very attention_grabbing. If you are mailing the letter, you can even use colorful envelopes printed with your logo. A famous one_liner or a logo that is not easily erased from memory creates magic for your products and services. Sales letter writing is more effective when properly formatted.