31 CFR § 19.725 - How much time do I have to contest a suspension?
(a) As a respondent you or your representative must either send, or make rrangements to appear and present, the information and argument to the suspending official within 30 days after you receive the Notice of Suspension.
(b) We consider the notice to be received by you -
(1) When delivered, if we mail the notice to the last known street address, or five days after we send it if the letter is undeliverable;
(2) When sent, if we send the notice by facsimile or five days after we send it if the facsimile is undeliverable; or
(3) When delivered, if we send the notice by e-mail or five days after we send it if the e-mail is undeliverable.