How to write or tell that collection of Email ID's has been attached.
It would be IDs. Were you to use the apostrophe (i.e, ID's), that would imply possession. If you're simply referring to a group of IDs, you drop the apostrophe.
As far as I know, there is no valid reason to put an apostrophe in IDs, as it is neither a possessive nor a contraction. It is simply a plural.