To set a fixed phone number, company and contact information in the mailbox, you can add a "personalized signature" in the mailbox, taking the computer QQ mailbox as an example, the method is as follows:

After the computer logs into the qq account, click the QQ email icon at the top of the main interface;

Enter the QQ email interface, and click the "Settings" button under the account at the top of the interface;

In the "General" interface, slide the page, find the column of "Personal Signature" and click "Add Personal Signature";

In the edit field of "New Personalized Signature", enter specific contact information such as telephone number and company, and click "OK";

After confirmation, click "Save Changes" in the lower left corner to save the used personalized signature settings.