You should expect that portfolio holdings may have (and in the case of older letters will have) changed since this date. (mjwhitman.pressbooks.com)
I've been looking for old letters for various projects and have yet to come across any! (theletteredcottage.net)
Read old letters of recommendation, LinkedIn endorsements, letters or notes from colleagues or teachers that have boosted your confidence in the past. (careerdigital.com)