How many years should I keep tax related supporting documents (such as email receipts of property tax payment, donation, etc)?

[VAer]

How many years should I keep tax related supporting documents (such as email receipts of county property tax payment, donation, etc)?

Can I delete anything older than 3 years? If there is audit, will it go beyond 3 years?

Yes, I am talking about gmail account. Sure, there is plenty of storage to keep those emails, but it is nice to delete some unnecessary message and keep mailbox clean/neat.

[Bsch4477]

3 years at a minimum. Some suggest 7 years. Documents supporting an adjustment of cost. As in a home or investments , for example, should be kept until the asset is sold. 

[VAer]

@Bsch4477  I am particularly talking about house property tax payment receipt (email), car property tax payment receipt (email), donation email receipt. 7 years for those three items?

Can I save them in PDF version(hard drive) instead of keeping them in gmail mailbox? I really want to clean up gmail mailbox.

[Bsch4477]

You can absolutely keep them in a pdf format. I keep mine for 3 years.