Art. 27 CISG
Unless otherwise expressly provided in this Part of the Convention, if any notice, request or other communication is given or made by a party in accordance with this Part and by means appropriate in the circumstances, a delay or error in the transmission of the communication or its failure to arrive does not deprive that party of the right to rely on the communication.
The Secretariat Commentary on Art. 25 of the 1978 New York Draft, predecessor to Art. 27 CISG, gives insight into the drafters' unterstanding on the eve of the 1980 Vienna Diplomatic Conference.
Overview of case law on Art. 27 CISG: UNCITRAL Digest
The UNCITRAL Digest on the CISG can be used as a starting point to discover the relevant case law on this article.