In addition to the above suggestions, I would like to add a few more:
Communicating Reasons for Resignation
The team members of the resigned person may be curious to know the reason for his exit. An employee may be leaving for better prospects, a job abroad, starting their own business, or shifting residence to another city, etc. You can communicate the reason in a positive manner with a single line.
Farewell Policy
Also, depending on the employee's association with the organization, if the company has a policy of offering a farewell to departing employees, you may mention this in the communication.