Problem is many of those are asking for emails or phone numbers of employers and many of those she worked for were 20 years ago or more.
Now in the old days she could just write in names and dates but now with computers, the programs kick it back because she doesnt have an email address (they need to verify).
If the system demands an email address then I would put her email address anywhere she does not have a current email address available for the contact.
If there is a section available to type a note I would point out the problem that no current emails exist for those places and (if possible) provide a name and phone and/or address where that person can be contacted. If no contact information is available any longer I would say that.
That or she needs to search and find a current email address she can use. Do as much work as possible. The prospective employer almost certainly won’t which could diminish her chances of getting the job.
Unless the job was highly specialised, I don’t think that what an applicant did 20 years ago is especially relevant, at least not to the point of needing to check.
I worked for the Emporium Stores for 17 years. That is until they closed their doors and now do not exists. I use to put down the information for the Emporium that I did have.
Is there a special case why she needs to say anything about such old employers? Most HR types say to go back three jobs or ten years, whichever is older.