A mailing address alone does not establish that sufficient physical premises have been secured for the intended operation. The evidence must explain the actual space and why it fits the business.
Assess function before labels
A shared-space or other arrangement needs fact-specific review; there is no universal office-size shortcut. Show what activities occur there, who will use it and when the company has access. The rest of the new-office requirements still matter, including the qualifying foreign managerial or executive year and the ability to support a qualifying U.S.
role within one year of approval. A mailing address does not describe an operation, and the expectation is that sufficient physical premises to house the new office have been secured. What sufficient means depends entirely on what the business proposes to do, so the analysis has to run from the plan rather than from a general idea of what an office looks like.
Assess function before labels: a registered-agent address, a mail-forwarding service and a virtual office each provide a place for correspondence and nothing more. A shared workspace, a serviced suite or a modest unit may be perfectly adequate where the operation genuinely fits. Establish what the space allows the business to do on day one.
And remember this is one requirement among several, since the qualifying relationship, the year of employment abroad and the nature of the proposed role all remain to be established.