Tex. Estates Code § 51.103

(a) Proof of service in each case requiring citation or notice must be filed before the hearing.

(b) Proof of service consists of:

(1) if the service is made by a sheriff or constable, the return of service;

(2) if the service is made by a private person, the person's affidavit;

(3) if the service is made by a qualified delivery method:

(A) the certificate of the county clerk making the service, or the affidavit of the personal representative or other person making the service, stating that the citation or notice was mailed, deposited with a private delivery service, or delivered by courier, as applicable, and the date of the mailing or deposit with the delivery service or the date of the courier delivery, as applicable; and

(B) the return receipt or other proof of delivery receipt attached to the certificate or affidavit, as applicable, if the sending was by a qualified delivery method and a receipt is available; and

(4) if the service is made by publication:

(A) a statement:

(i) made by the Office of Court Administration of the Texas Judicial System or an employee of the office;

(ii) that contains or to which is attached a copy of the published citation or notice; and

(iii) that states the date of publication on the public information Internet website maintained as required by Section 72.034, Government Code; and

(B) an affidavit:

(i) made by the publisher of the newspaper in which the citation or notice was published or an employee of the publisher;

(ii) that contains or to which is attached a copy of the published citation or notice; and

(iii) that states the date of publication printed on the newspaper in which the citation or notice was published.