Hello, removing compression = zlib did fix the starting issue for v5.44, update worked, thanks. Is 'deflate' affected too? Is compression recommended at this stage of mail processing? Thanks once more, regards!

Hello, The compression is not recommended with TLS because of the CRIME or BREACH attacks. From stunnel v 5.44 in Windows the zlib compression is not supported. So you should remove the option: compression = zlib

If you want to use this compression, please place the file zlib1.dll (from the previous version) in the stunnel / bin directory.

Best regards, Malgorzata