However, it is best to get the original invitation letter. After all, the original invitations in the United States are all watermarked or anti-counterfeiting, which is more convincing.

If the other party sent it to you by FedEx/UPS express, you'd better ask Tracking No, so that you can check the location and arrival date of the express.

If there is really no original version, the electronic version will do. In fact, whether you can get a visa or not is only one factor, and other materials are equally important. If you have a booth at a foreign exhibition, you are more likely to get a visa.