Do you believe the email program on your computer that says “delivery complete” a few seconds after you hit the “send” button? If you do, you’ve made the classic email mistake. Your computer may think it’s been “sent,” but that’s not the real question. The real question is whether or not the email has been received.
Let’s examine the rules of two forums: First, the appellate rules of the Small Business Administration (“SBA”) Office of Hearings and Appeals (“OHA”), which adjudicates protest appeals by size. Second, the bid protest rules of the Government Accountability Office (“GAO”), which adjudicates most bid protests:

OHA: (a) Filing and notification methods. Email, postal mail, delivery, and facsimile are permitted, unless otherwise ordered by a judge…
This is what happens when you can’t confirm receipt of your email on the forum. In Size Allure of Provisions, Presently, SBA No. Siz-5655, 2015 WL 2149481 (April 20, 2015), Supplies Now attempted to appeal a size determination that they believed was incorrect (it had been dismissed as untimely because more than five working days following the notification of the award). Supplies Now received the sizing determination on February 3, 2015. On February 18, 2015, Supplies Now filed its appeal via email and received an acknowledgment from its email account stating “Delivery to recipients or groups is complete, but no delivery notification received.” sent by the destination server. [OHA’s email address is among those on the acknowledgment].” After about six weeks and nothing from OHA, Supplies Now called OHA and was told the appeal had not been received. Suministros ahora retransmitted its appeal request on April 9, 2015.

In dismissing the appeal as untimely, OHA noted that pursuant to 13 C.F.R. § 134.304(a), a sizing appeal must be filed with OHA within 15 days of receiving the sizing determination, and Supplies Now did not do so, as nothing was received within 15 days. “[Having elected to send his appeal by email, Appellant was responsible for ensuring that the email successfully reached OHA. Appellant also could not reasonably rely solely on the acknowledgment of its email system, particularly since Appellant received no response, over a period of several weeks, from OHA or other intended recipients of the appeal.”
Note that the GAO rules (set forth above) comparably emphasize that a document is not filed until the GAO receives it, including documents sent by email.
The lesson is straightforward: If you email something to OHA or GAO, always confirm by phone that it has been received. Don’t trust a computer-generated confirmation, or even an “acknowledgment” sent by an email program. Phone the forum, get the name and phone number of the person at GAO or OHA, and make sure all pages have been received.