All notices or other communications hereunder shall be in writing and shall be deemed to have been duly given (a) when delivered personally, (b) upon confirmation of receipt when such notice or other communication is sent by facsimile or telex, (c) one day after timely delivery to an overnight delivery courier, or (d) on the fifth day following the date of deposit in the United States mail if sent first class, postage prepaid, by registered or certified mail.