VERY VERY URGENT help please

[Apeksha]

My parents are travelling tomorrow

They are coming the second time to USA

These are the documents that they would be carrying

1. Passport
2. Visa
3. Scanned copy of Invitation letter from me
4. their office ID and leave letter
5. airline ticket

IS ANY OTHER DOCUMENTS REQUIRED AT THIS POINT?

ALSO I COULD ONLY SEND A SCANNED COPY OF INVITATION LETTER.
I WAS NOT ABLE TO SEND BY POSTAL MAIL AS IT WILL DELAY . wILL THAT BE A PROBLEM??

PLEASE SUGGEST ANY ONE?

[txh1b]

An invite could even be an email. CBP knows no one uses snail mail these days and is not a problem.

Invite letter is just a good to have document and is never looked at.