https://docs.microsoft.com/en-us/openspecs/exchange_server_protocols/MS-OXPSVAL/f894e839-22a2-4f72-a1af-a7de40089bc8 Specifies the Email Postmark Validation Algorithm, which creates and validates computational puzzles to reduce the effectiveness of junk email. https://docs.microsoft.com/en-us/openspecs/exchange_server_protocols/MS-OXPSVAL/f894e839-22a2-4f72-a1af-a7de40089bc8 <b>Protocol Revision:</b> 18.0<br/><b>Downloads:</b><br/><ul style="list-style-type: square;"><li><a href="https://msopenspecs.azureedge.net/files/MS-OXPSVAL/[MS-OXPSVAL].pdf">PDF</a></li><li><a href="https://msopenspecs.azureedge.net/files/MS-OXPSVAL/[MS-OXPSVAL]-240416.docx">DOCX</a></li></ul> Tue, 16 Apr 2024 MS-OXPSVAL-20240416 https://docs.microsoft.com/en-us/openspecs/exchange_server_protocols/MS-OXPSVAL/f894e839-22a2-4f72-a1af-a7de40089bc8 <b>Protocol Revision:</b> 17.0<br/><b>Downloads:</b><br/><ul style="list-style-type: square;"><li><a href="https://msopenspecs.azureedge.net/files/MS-OXPSVAL/[MS-OXPSVAL]-220215.pdf">PDF</a></li><li><a href="https://msopenspecs.azureedge.net/files/MS-OXPSVAL/[MS-OXPSVAL]-220215.docx">DOCX</a></li></ul> Tue, 15 Feb 2022 MS-OXPSVAL-20220215 https://docs.microsoft.com/en-us/openspecs/exchange_server_protocols/MS-OXPSVAL/f894e839-22a2-4f72-a1af-a7de40089bc8 <b>Protocol Revision:</b> 17.0<br/><b>Downloads:</b><br/><ul style="list-style-type: square;"><li><a href="https://msopenspecs.azureedge.net/files/MS-OXPSVAL/[MS-OXPSVAL]-210817.pdf">PDF</a></li><li><a href="https://msopenspecs.azureedge.net/files/MS-OXPSVAL/[MS-OXPSVAL]-210817.docx">DOCX</a></li></ul> Tue, 17 Aug 2021 MS-OXPSVAL-20210817 https://docs.microsoft.com/en-us/openspecs/exchange_server_protocols/MS-OXPSVAL/f894e839-22a2-4f72-a1af-a7de40089bc8 <b>Protocol Revision:</b> 16.0<br/><b>Downloads:</b><br/><ul style="list-style-type: square;"><li><a href="https://msopenspecs.azureedge.net/files/MS-OXPSVAL/[MS-OXPSVAL]-210422.pdf">PDF</a></li><li><a href="https://msopenspecs.azureedge.net/files/MS-OXPSVAL/[MS-OXPSVAL]-210422.docx">DOCX</a></li></ul> Thu, 22 Apr 2021 MS-OXPSVAL-20210422 https://docs.microsoft.com/en-us/openspecs/exchange_server_protocols/MS-OXPSVAL/f894e839-22a2-4f72-a1af-a7de40089bc8 <b>Protocol Revision:</b> 15.0<br/><b>Downloads:</b><br/><ul style="list-style-type: square;"><li><a href="https://msopenspecs.azureedge.net/files/MS-OXPSVAL/[MS-OXPSVAL]-181001.pdf">PDF</a></li><li><a href="https://msopenspecs.azureedge.net/files/MS-OXPSVAL/[MS-OXPSVAL]-181001.docx">DOCX</a></li></ul> Mon, 01 Oct 2018 MS-OXPSVAL-20181001 https://docs.microsoft.com/en-us/openspecs/exchange_server_protocols/MS-OXPSVAL/f894e839-22a2-4f72-a1af-a7de40089bc8 <b>Protocol Revision:</b> 14.0<br/><b>Downloads:</b><br/><ul style="list-style-type: square;"><li><a href="https://msopenspecs.azureedge.net/files/MS-OXPSVAL/[MS-OXPSVAL]-180724.pdf">PDF</a></li><li><a href="https://msopenspecs.azureedge.net/files/MS-OXPSVAL/[MS-OXPSVAL]-180724.docx">DOCX</a></li></ul> Tue, 24 Jul 2018 MS-OXPSVAL-20180724 https://docs.microsoft.com/en-us/openspecs/exchange_server_protocols/MS-OXPSVAL/f894e839-22a2-4f72-a1af-a7de40089bc8 <b>Protocol Revision:</b> 13.0<br/><b>Downloads:</b><br/><ul style="list-style-type: square;"><li><a href="https://msopenspecs.azureedge.net/files/MS-OXPSVAL/[MS-OXPSVAL]-160914.pdf">PDF</a></li><li><a href="https://msopenspecs.azureedge.net/files/MS-OXPSVAL/[MS-OXPSVAL]-160914.docx">DOCX</a></li></ul> Wed, 14 Sep 2016 MS-OXPSVAL-20160914 https://docs.microsoft.com/en-us/openspecs/exchange_server_protocols/MS-OXPSVAL/f894e839-22a2-4f72-a1af-a7de40089bc8 <b>Protocol Revision:</b> 13.0<br/><b>Downloads:</b><br/><ul style="list-style-type: square;"><li><a href="https://msopenspecs.azureedge.net/files/MS-OXPSVAL/[MS-OXPSVAL]-160613.pdf">PDF</a></li><li><a href="https://msopenspecs.azureedge.net/files/MS-OXPSVAL/[MS-OXPSVAL]-160613.docx">DOCX</a></li></ul> Mon, 13 Jun 2016 MS-OXPSVAL-20160613