Files with i2s file extension can be found as Invision for mIRC settings files. Probably obsolete.
I2S file extension - Invision for mIRC settings
What is i2s file? How to open i2s files?
File type specification:
The i2s file extension was used for some sort of Invision for mIRC settings file type, which seems to be obsolete as no further information about it could be found.
This i2s file type entry was marked as obsolete and no longer supported file format.
This type of file is no longer actively used and is most likely obsolete. This is typically the case for system files in old operating systems, file types from long discontinued software, or previous versions of certain file types (like documents, projects etc.) that were replaced in higher versions of their original programs.