Salt Lake Mail. A Correspondent informs us, that no Mail had passed Fort Kearney from Salt Lake, since December last; and also states that the Mail for March en route for the Valley, went as far out as the Big Blue, and in consequence of high water returned to Independence. Phelp's train of twelve wagons, ten mules to each, passed the Fort on the 15th ult., with merchandise for Utah. The April Mail for the Valley, passed the Fort on the 15th of last month, in charge of Mr. Phelps of Independence, Mo. The following named persons also passed for the North Platter River Bridge; William and T. Randall, with groceries and provisions for emigrants; J. B. Nichols, for Fort Laramie; Richards & Co., with provisions, &c. Mr. Futs left Fort Laramie on the 10th March, for Salt Lake, with nine wagons loaded with Bacon. Plenty of Buffalo within three hours ride of the Fort.