submit I-407

Hi Mr 8,

Last time I mentioned I decided to re-apply green card for my father, he need submit I-407 first, then I can submit I-130 for him. I still have one question. When I downloaded the I-407 from the website below, the 'where to file' section says the form can be mailed to Guangzhou or Beijing Field office too. Is there any special reason to submit I-407 in person? Since my father is old, it is good if the traveling could be avoided.

https://www.uscis.gov/i-407

Thank you very much!