It depends. If the notification letter is issued by a natural person, it can be signed by the natural person, and there is no need to seal it. If it is issued by a legal person and other institutions, it needs to be stamped with the official seal to be effective. A notification letter is a document issued to inform the parties of certain matters. There are many kinds of notification letters. For example, a contract is a notice of termination. This contract shall be terminated after the notice is served on both parties.

According to the regulations, the contract can be terminated under any of the following circumstances:

1, the parties reach an agreement to terminate the contract;

2. Terminate the contract when the conditions agreed by both parties are met;

3. The purpose of the contract cannot be achieved due to force majeure;

4. Before the expiration of the performance period, one party clearly indicated or indicated by his own behavior that he would not perform the main debt;

5. One party delays the performance of the main debt and fails to perform it within a reasonable period after being urged;

6. One party delays the performance of debts or commits other breach of contract, which makes the purpose of the contract impossible to achieve;

7. Other circumstances.

Legal basis:

People's Republic of China (PRC) Civil Code

Article 490

If the parties enter into a contract in the form of a contract, the contract shall be established when the parties sign, seal or press their fingerprints. Before signing, sealing or fingerprinting, one party has fulfilled its main obligations, and the contract is established when the other party accepts it. A contract shall be concluded in written form as stipulated by laws, administrative regulations or agreed by the parties. If the parties do not do this in writing, but one party has fulfilled its main obligations and the other party accepts it, the contract is established.