I believe you meant the IRS Form 3520, Annual Return To Report Transactions With Foreign Trusts and Receipt of Certain Foreign Gifts.
The Form 3520 is mailed separately from your personal tax return. So you can e-file your personal tax return.
You must Sign and date the form 3520 and It is mailed to -
Internal Revenue Service Center
P.O. Box 409101
Ogden, UT 84409
IRS Form 3520 - https://www.irs.gov/forms-pubs/about-form-3520
