Keep in mind that this is a stamp of the attorney’s signature, not just the attorney’s name, so using an attorney signature stamp is the equivalent of a paralegal signing the attorney’s name “by permission.” For letters that do not include legal advice or that deal with some administrative matters, using a stamp is probably fine. However, using an attorney stamp on pleadings, engagement letters, settlement offers and documents, correspondence that includes legal advice and particular court documents is never appropriate. If you have any doubt as to the use of an attorney signature stamp, insist that the attorney sign the document. It is always safer, and never incorrect, to have an original attorney signature.
The Texas Criminal Court of Appeals has held that the use of a signature stamp on a notice of appeal was “ineffective to show personal authorization” and did not “comply with the legislatively mandated guarantee that the only person permitted by statute to make an appeal on behalf of the State actually participated in the process.” See State of Texas v. Shelton, 830 S.W.2d. 605 (Tex. Crim. App. 1992). See also State of Texas v. Roberts, 940 S.W. 2d 655 (Tex. Crim. App. 1996). The logical assumption from these cases is that is is never correct to use an attorney’s signature stamp on a pleading, settlement agreement, or other official document, even if the attorney instructs you to do so.