I need to send a copy of my form 3115 to the IRS national office today. The address I have is: Internal Revenue Service Attn: CC:IT&A (Automatic Rulings Branch) P.O. Box 7604 Ben Franklin Station Washington, DC 20044 I have heard rumors of problems delivering certified mail, return receipt requested, to IRS P.O. boxes......anybody had any problems with this? Should I not send it certified mail?