RPost, a provider of electronic signature services, on Tuesday said it filed a suit against Adobe Systems Inc. and its new acquisition, EchoSign, alleging patent infringement.

The Los Angeles company, which has sued other companies on similar grounds, contends that EchoSign is infringing on five of its U.S. patents. The suit was filed after Adobe of San Jose announced Monday that it had acquired EchoSign, a Palo Alto developer of web-based electronic signature software, for an undisclosed amount.

RPost, which was founded in 2000, said that it holds 35 patents with worldwide coverage. It specializes in electronic signature and registered e-mail services that the company claims leaves senders with court-admissible evidence of e-mail content, timestamp and delivery.

“The key element in any system of electronic signature is creating a legally meaningful audit trail of every step of the signature process and associating that audit trail with particular electronic document content,” Chief Executive Zafar Khan said in a statement. “We pioneered the technology for proof of e-mail and document delivery, including recording recipient reply or signoff on the message content, and have the patents to prove it.”

The lawsuit, which was filed in U.S. District Court for the Eastern District of Texas, seeks an injunction against Adobe to prevent further damage to RPost’s business by EchoSign. Adobe declined comment on the pending litigation.

RPost last month sued RightSignature of Santa Barbara and DocuSign of Seattle over the same patents.