Before litigation, you can ask a notary office to collect evidence and make a notarized document; Or apply to the people's court for pre-litigation evidence preservation. The best way to obtain evidence is to look at the source code and copy all the contents and paste them into the word processing software for editing and printing, so as to obtain all the contents in the mail; The contents in the annex should be printed out with high-grade equipment as far as possible without distortion according to different file formats; If it is a sound file, it can be recorded as text and printed out, and the original sound file can be kept for future trial cross-examination. In a lawsuit, the parties may submit the exported mail to the people's court on a floppy disk. If there is no objection after cross-examination by the other party, it can be printed and signed by both parties. If the other party disagrees, the people's court shall collect evidence in person, and the evidence may be obtained by on-site inspection, and the record of on-site inspection shall be signed by both parties on the spot. If the parties only submit the printed manuscript, and the original has been permanently deleted from the computer, unless the other party approves it, the printed manuscript can not be used as the basis for finalizing the case regardless of whether the other party has the ability to disprove it, because it is impossible to judge whether it is the original. At this time, the evidence cannot be confirmed to be valid because the other party can't prove the contrary. Nowadays, the fastest developing technology is computer-related technology, which is really changing with each passing day. For example, the postmark of e-mail and the electronic signature that can be encrypted have been invented, so it is not far from being applied in e-commerce. The author believes that in the trial practice, we should pay special attention to the characteristics of e-mail, such as platform, application software and transmission technology, which will play a direct and decisive role in the identification of e-mail. Therefore, the legal profession should follow the latest development of technology and constantly adjust the corresponding countermeasures. At present, in business activities, we should pay attention to: computers used for business activities should be used by special people as much as possible to avoid leaking business secrets or important documents being mistakenly deleted by others. As far as possible, encrypt the email, at least the relevant content should be made into a separate file and encrypted, and the password should be told to the other party in other ways. In the software for sending and receiving e-mails, it is best to create a subfolder with a business project or a business partner, which is convenient for finding relevant contents and is not easy to be deleted by mistake. Important mail should be backed up separately. Reinstall the computer system, etc. to back up all the mail.