It is legal to ask for contributions this way, but could cause confusion if the IRS were to audit a donor and not find the trade name on the list of exempt organizations.  The organization can deal with this problem by stating on all of its receipts and acknowledgments that the name they are using is a trade name of the organization whose legal name is on the IRS list.  If it does all of its business under the trade name, it could also note the “doing business as” name on the Form 990 tax information return.

The organization should be sure that the trade name is included in the registration material submitted to each state in which it is required to register to solicit contributions.  Most state charitable solicitation registration laws require disclosure of any name under which the organization solicits.