OPINION

State prisoner McKinney filed suit under the Civil Rights Act, 42 U.S.C. § 1983 , for himself, his mother Viola and another state prisoner Wimberley 1 against 23 employees of the California prison system, a lawbook publishing company and one of its employees. He alleged 10 substantive counts and one count for punitive damages. Of the 10 substantive counts, 9 concerned actions of the prison officials, largely involving allegations of denial of access to various legal materials. Apparently McKinney was substantially involved in giving advice and preparing legal documents for himself and others. In the remaining substantive count McKinney alleged that the lawbook publishing company and one of its salesmen had conspired with prison officials to prevent him from receiving lawbooks his mother had purchased for him. As a result of defense motions for dismissal and summary judgment, the trial court disposed of the case in favor of defendants-appellees. McKinney v. DeBord, 324 F.Supp. 928 (E.D.Cal.1970).

Although the notice of appeal purports to be on behalf of all plaintiffs, it is signed only by McKinney. The notice of appeal must be signed by the party or the party’s attorney. Fed.R. Civ.P. 11. See Wilson v. Dixon, 256 F.2d 536 (9th Cir.), cert. denied, 358 U.S. 856 , 79 S.Ct. 89 , 3 L.Ed.2d 90 (1958). Since McKinney is not an attorney, the purported appeals by Viola McKinney and Wimberley must be dismissed and it is so ordered. Additionally, since McKinney is no longer incarcerated, his request for declaratory judgment and his allegations concerning prison conditions are moot. As to the remaining issues, we agree basically with the disposition by the district court, but we feel it necessary to amplify the lower court’s treatment of the case on several of McKinney’s claims. With the specific exception discussed below, we affirm.

In count three, McKinney claims that prison officials refused to allow him to show his mother certain catalogues and brochures from lawbook companies. The district court dismissed this count as failing to state a cause of action upon which relief could be granted because it found that McKinney’s intention was to have her buy “legal books which he intended to keep in his cell” and that he “was seeking to purchase more books than he was permitted to possess in his cell under applicable prison regulations . . . .” 324 F.Supp. at 932 .

We are admonished by the oft-repeated 2 rule of Conley v. Gibson, 355 U.S. 41, 45-46 , 78 S.Ct. 99, 102 , 2 L.Ed.2d 80 (1957), that a complaint should only be dismissed under Fed.R. Civ.P. 12(b)(6) if “it appears beyond doubt that the plaintiff can prove no set of facts in support of his claim which would entitle him to relief.” That, of course, requires that every factual difference be resolved in the plaintiff’s favor. 5 C. Wright & A. Miller, Federal Practice and Procedure § 1357 at 601 (1969). In line with this rule, we suppose that it is conceivable McKinney could have had a legitimate purpose in having his mother purchase the law books for him — one which would not have entailed violation of the prison regulation limiting at sixteen the number of books a prisoner could have in his cell. He could have wished to replace books in *504 his cell with those his mother would purchase, thereby staying within the sixteen book limit; or he might possibly have donated the newly acquired volumes to the prison library, also a permissible form of access to law books. See In re Harrell, 2 Cal.3d 675 , 697 & n. 23, 87 Cal.Rptr. 504, 518-519 , 470 P.2d 640, 654-655 (1970), cert. denied, 401 U.S. 914 , 91 S.Ct. 890 , 27 L.Ed.2d 814 (1971).

But, in construing a complaint most favorably for the plaintiff, a court need not give a. plaintiff the benefit of every conceivable doubt; rather, a court is required only to draw every reasonable or warranted factual inference in the plaintiff’s favor. 3 And the same rule which requires us to apply “less stringent” standards to pro se complaints “than [to] formal pleadings drafted by lawyers,” Haines v. Kerner, 404 U.S. 519, 520 , 92 S.Ct. 594, 596 , 30 L.Ed.2d 652 (1972), also teaches that we should use common sense in interpreting the frequently diffuse pleadings of pro se complainants. Cf. Weller v. Dickson, 314 F.2d 598 , 601—602 (9th Cir.) (Duniway, J., concurring), cert. denied, 375 U.S. 845 , 84 S.Ct. 97 , 11 L.Ed.2d 72 (1963). 4

With this in view, it is clear here that the district court was correct in finding that it was McKinney’s intention to purchase books for his cell. McKinney, in both his brief here and his memoranda filed below, makes it evident that it was never his intention to have his mother replace books in his cell library or to donate them to the prison library. 5 Nowhere does McKinney argue other than that he intended to purchase the books for his cell.

Thus, interpreting the third count of McKinney’s complaint in a common sense manner, we affirm the district court’s dismissal of it. We would be blind to the realities of this case were we to do otherwise and hypothetically assume that McKinney had some other factual possibility in mind in his complaint than that which he repeatedly declares in his arguing papers. Cf. S & S Logging Co. v. Barker, 366 F.2d 617, 623 (9th Cir. 1966).

McKinney complains in counts five and seven that prison officials denied his First Amendment rights by seizing letters sent by him to the law book company. These letters protested that the company had not sent 42 books McKinney had previously ordered. Earlier, after a consultation with prison officials revealed that it would violate prison regulations for McKinney to receive the books, the company had declined to send them to McKinney; instead, it shipped them to his mother. At the time the letters were seized, McKinney had already sent several other messages ob *505 jecting to the actions of Bancroft Whitney, and according to the complaint, these had not been suppressed.

Recently, in Procunier v. Martinez, 416 U.S. 396 , 94 S.Ct. 1800 , 40 L.Ed.2d 224 (1974), the Supreme Court ruled on the extent to which prisoner correspondence can be censored or suppressed. It held that censorship regulations “must further an important or substantial governmental interest unrelated to the suppression of expression” and “the limitation of First Amendment freedoms must be no greater than is necessary or essential to the particular governmental interest involved.” Id. at 413 , 94 S.Ct. at 1811 .

Under this standard we do not think the suppression of the letters violated McKinney’s (or the publisher’s) First Amendment rights. The letters were sent only to prompt the law book publisher to send the volumes McKinney had ordered. Receipt of the books would have caused McKinney to be in violation of prison regulations. The letters were seized only after it became clear that the correspondence could well prompt violation of a valid prison regulation and hence seizure was an aid to enforcement of the sixteen book limit. Their seizure thus furthered an important governmental interest unrelated to the suppression of expression.

Our conclusion is strengthened by prison regulations approved by the three judge court in Martinez which would seemingly legitimate what the prison authorities did here. The regulations, which were cited approvingly by the Supreme Court as “indicative of one solution to the [censorship] problem,” allow authorities to censor any outgoing letter if it “concerns plans for activities in violation of institutional rules.” Procunier v. Martinez, 416 U.S. at 416 n. 15, 94 S.Ct. at 1813 . That proscription is applicable to McKinney’s repetitious letters of complaint.

However, the Supreme Court in Martinez also required that when delivery of a letter is withheld, certain procedural safeguards be supplied. Id. at 417 — 419, 94 S.Ct. at 1814 . The Martinez district court had defined the procedural minimum as notice of rejection of the letter to the inmate and an opportunity to protest to a prison official other than the person who originally disapproved of the correspondence, id. at 418-419 , 94 S.Ct. at 1814 ; the Supreme Court approved of these safeguards as not “unduly burdensome.” Id. In McKinney’s case no procedural safeguards were provided, which is understandable in that the censorship here substantially predated Martinez . Thus it may well be that the failure to provide safeguards was the result of good faith enforcement of the then valid prison rules on mail censorship, a fact which would immunize the conduct of the prison officials under § 1983. See, e. g., Wimberley v. Campoy, 446 F.2d 895 (9th Cir. 1971). But, we cannot so conclude with utter certainty. Since this count was dismissed by way of a Rule 12(b)(6) motion, we are therefore forced, under the principle of Conley v. Gibson, to remand on this limited issue for further proceedings.

McKinney separately appeals the dismissal of his cause of action against the law book publisher and its representative. Assuming timely notice of that appeal was filed, see Fed.R.App.P. 3, 4, the appeal is frivolous.

Affirmed in part; reversed and remanded in part.

. McKinney also attempted to plead a class action, but he neither succeeded nor perfected his right to proceed. See Fed.R.Civ.P. 23(c)(1).

. See, e. g., DeWitt v. Pail, 366 F.2d 682, 685 (9th Cir. 1966).

. See Hiland Dairy, Inc. v. Kroger Co., 402 F.2d 968, 973 (8th Cir. 1968), cert. denied, 395 U.S. 961 , 89 S.Ct. 2096 , 23 L.Ed.2d 748 (1969); Ryan v. Scoggin, 245 F.2d 54, 57 (10th Cir. 1957); Ogden River Water Users’ Ass’n v. Weber Basin Water Conservancy, 238 F.2d 936, 940 (10th Cir. 1956); International Bank of Miami v. Banco de Economias y Prestamos, 55 F.R.D. 180, 186 (D.Puerto Rico 1972); Herman v. C. O. Porter Machinery Co., 333 F.Supp. 416, 417 (M.D.Pa.1971); cf. Margetta v. Pam Pam Corp., 354 F.Supp. 158 (S.D.Cal.1973).

. See also Smart v. Heinze, 347 F.2d 114 , 116 n. 2 (9th Cir.), cert. denied, 382 U.S. 896 , 86 S.Ct. 192 , 15 L.Ed.2d 153 (1965).

. In his brief here McKinney put the third claim as follows:

Br. at 20. In a memorandum filed in the lower court McKinney negatived any intention to have his mother replace volumes in his cell:

Cl.R. at 399.