From "General Instructions;" page two of Form 8948:
When a return is considered filed by a preparer. For the e-file requirement, a return is considered filed by a preparer if the preparer or any member, employee, or agent of the preparer or the preparer's firm submits the tax return to the IRS on the taxpayer's behalf, either electronically or in the paper format. For example, the act of submitting includes having the preparer or a member of the preparer's firm drop the return in a mailbox for the taxpayer. Acts such as providing filing or delivery instructions, an addressed envelope, postage estimates, stamps, or similar acts designed to assist the taxpayer in the taxpayer's efforts to correctly mail or otherwise assist the taxpayer in the taxpayer's efforts to correctly mail or otherwise deliver a paper return to the IRS do not constitute filing by the preparer as long as the taxpayer actually mails or otherwise delivers the return to the IRS.
When a return is considered filed by a preparer. For the e-file requirement, a return is considered filed by a preparer if the preparer or any member, employee, or agent of the preparer or the preparer's firm submits the tax return to the IRS on the taxpayer's behalf, either electronically or in the paper format. For example, the act of submitting includes having the preparer or a member of the preparer's firm drop the return in a mailbox for the taxpayer. Acts such as providing filing or delivery instructions, an addressed envelope, postage estimates, stamps, or similar acts designed to assist the taxpayer in the taxpayer's efforts to correctly mail or otherwise assist the taxpayer in the taxpayer's efforts to correctly mail or otherwise deliver a paper return to the IRS do not constitute filing by the preparer as long as the taxpayer actually mails or otherwise delivers the return to the IRS.