You'd better put a stamp on it. If you write a letter of recommendation in this way, the leader should also sign it. The signature should be at the lower right of the paper, and the company name should be written under the signature, such as * * * * * * * * *. Putting the seal on the company name is the most standard. Remember to write the company name and seal exactly the same, not a word difference, it is best to write it on the title paper of the company, and it should be the same as the official seal. Because foreigners are more rigorous in doing things, if your name is missing one or two words, they will think it is suspected of fraud.

As for envelopes, it's better to put stamps on them. It doesn't matter whether it is written on the surface or not, mainly because the page of recommendation must be written well.