In Slusher v. Durrer (1977) 69 Cal.App.3d 747, the plaintiff obtained a default judgment against the defendant on her civil complaint alleging assault and battery. The defendant had been personally served with the civil complaint when he appeared to defend against the misdemeanor assault and battery charges. (Id. at p. 750.) Plaintiff's section 587 declaration of mailing the request for entry of default, however, indicated that defendant's address was "unknown" to plaintiff and her attorney. (Slusher, supra, at p. 750.) The defendant successfully moved to set aside the default, and the declaration he submitted in connection with that motion presented ample evidence to establish that his mailing address was readily obtained. In opposition, "the declarations filed by plaintiff and her counsel do not reveal any effort by the plaintiff to ascertain defendant's mailing address, although several of defendant's relatives and acquaintances frequented plaintiff's place of business. The effort expended by her counsel disclosed at best a minimal search or inquiry of known available sources." (Id. at p. 756.) It was in this context that the court held that the mailing requirement of section 587 is analogous to "the necessary predicates to secure the right to effect service by publication." (Slusher, supra, at p. 756.) "Section 415.50 requires a showing that 'reasonable diligence' was exercised in the attempt to locate the litigant upon whom personal service should be made. A comment to the ... section 415.50 requirement of reasonable diligence indicates that a 'thorough, systematic investigation and inquiry' be conducted in good faith. No less an inquiry is required by section 587. Available sources such as city and county directories, utility companies, friends, acquaintances, or relatives or licensing offices (for example the Department of Motor Vehicles license registration) must be checked for a mailing address. Such an inquiry would satisfy the minimum requirement." (Ibid.)