The following is my timeline for 221(g):
12/16/2019- Dropbox appointment for H1 transfer/extension
12/19 - passport returned with white slip to appear for interview
12/30 - given 221(g) blue slip at interview in New Delhi Embassy
1/6/2020- submitted documents(client letter etc) through email
My question is: Whenever they are ready for the next step (hopefully passport submission for issuing visa), do they send email to the same id which I had used to send the documents? Also, who is the sender? Is it ustraveldocs?