Libeay32.dll is used by mIRC to connect to SSL IRC servers. Even though it may not be 'currently' using the DLL (as in, maintaining a connection) I believe mIRC initializes the dll routines at startup to speed up SSL connections later on.
I'm not sure how to get mIRC to use the openSSL DLL in your C:\ directory, but placing a copy of the dll in the same directory as mIRC.exe should force mIRC to use that dll instead of falling back to libeay32.dll or looking in the system folder for an openSSL dll
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Edited to expand on 'portable'":
mIRC 'portable' mode just means mIRC will use the directory its stored in to reference, save and/or load mIRC specific files(scripts, config, etc). mIRC still has dependencies that are included with Windows, or that Windows Abstracts. IE: GUI elements, SSL, etc.
That is to say, "Portable Mode" does not mean a copy of everything mIRC needs to function will be included with the installation.
Last edited by FroggieDaFrog; 17/04/14 09:28 PM.