The EULA says you can redistribute mIRC as long as you don't modify it and contact Khaled:
mIRC may only be distributed as part of the original mIRC install file as distributed by mIRC Co. Ltd. mIRC and the mIRC install file may not be distributed as a part of any package and may not be modified, decompiled, disassembled, or reverse engineered.
If you would like to distribute mIRC as part of a magazine, book, cd-rom, website, or any other form of distribution, you must contact mIRC Co. Ltd. for written authorization.
In other words, the official response is: email Khaled and ask.
Practically speaking, though, there are at least a few existing sites that archive old versions of mIRC... and I don't think they got explicit authorization from Khaled-- but I cannot confirm this-- just a feeling I get. Frankly, I'm not even sure how strong a redistribution clause is in the license agreement to begin with, given that you are simply making something available which was freely obtained (free as in freedom, not $$$) on a website. If archive.org is allowed to redistribute html pages from old websites, the same freedom should apply to anything else downloaded from those sites. I'm no lawyer, though.
I would assume that the general rule of thumb is: (1) don't misrepresent mIRC, (2) don't modify the redistributables, (3) take the site down if Khaled asks you to. If you follow those steps, I don't think you should have anything to worry about. Khaled has historically been pretty accepting of people redistributing mIRC as long as they were doing so with good intentions.
