If you really don't need old email, then don't bother, but for the chance that you do need them sometimes, but don't want to store everything in an internet con

If you really don't need old email, then don't bother, but for the chance that you do need them sometimes, but don't want to store everything in an internet connected place - it would be an option setting up a old laptop for this(maybe with Thunderbird), where you can remove the wifi chip for this air gapped use case. (In most older laptops they are easy to remove and not soldered on.) Then regulary exporting all the needed files, either just copy them with a USB stick and more secure would be burning CD-R's for each data transfer. And it likely helps having an exotic linux system on the laptop, so a windows USB worm won't replicate there if you use the pragmatic USB data transfer variant.