Legal advice! What should former employees do if they send emails to their bosses and foreign customers, defaming their personality and affecting the company's image?

First, according to your description, the emails sent by former employees are all directed at the boss of the company, which is an infringement. If the impact is serious, it may be suspected of libel and insult.

Second, try to collect the emails sent by this person to others as evidence, especially some emails suspected of fabricating facts and deliberately slandering, go to the police station or the public security brigade to call the police and ask the public security organs to intervene.

Third, this kind of behavior belongs to civil infringement of reputation. Collect the emails sent by them, go to court to sue, demand to stop the infringement and compensate for the losses.