Have you ever had an experience to buy items on the internet and pay with Visa/Master card? Visa/Master card is a popular method for people over the world to purchase something online. Sometime you also get some failures during processing as well because of your internet is slow down or your Visa/Master card number is typed wrongly. To resolve this problem you have to re-pay again once you see that your internet connection is enough faster than or Visa/Master card number and its expiry date is correct.
Importantly, E-mails address also are used to send and receive messages by other millions different companies around the world per each second. We see that the number of these transactions, per each second, it is very hug and large. I think that there are at least 20% are going into spam box or junk mail box, other 60% are going correctly into mail box but there is 20% I expect that it will be failed exactly because I think that sometime the email address are written incorrectly or the e-mail transactions are stuck in any each second by slow internet connection or something else, so that causes it cannot send out.
Anyway, as the information is shown on the website that Cambodia e-Visa use e-mail address and reference number as important method to check e-Visa status whether it is approved or not approved, moreover it is used to download e-Visa certificate after approval also. You are required to spell and provide your e-mail address correctly before applying for e-Visa to Cambodia so that e-Visa officers can send e-Visa certificate to you as soon as possible or else e-Visa certificate will not be sent.
And in case you don't get your e-Visa certificate after applied for 3 working days thru your e-mail address so your are recommended to go to "Check & Change" link on e-Visa homepage by filling up your reference number and e-mail address to download it. [See picture]
The official Cambodia e-Visa website http://www.mfaic.gov.kh/evisa/