^^^ what glc said is exactly right. Apps are installed in /data and with only 193MB free you are effectively out of space. The system needs a minimum amount of free space for operation or it becomes unstable.
You need to make room. You're just gonna have to make some decisions.
Clearing cache files is not a solution. It's the Fool's gold of making space. Fool's gold is not real gold and space made by clearing caches is not real space. It will only make space temporarily since cache files will rebuild over time. Also, while clearing cache files won't hurt anything, they're there to speed up operation and should be left alone.
These are things that can help make significant additional space:
I think with every fairly recent email app I've ever seen, you can set limit on how much email is synced (downloaded) to the phone, either by date received or number of emails. Check this to see if it keeps email from certain people too long or an excessive number of emails.
To make space you can also:
Delete texts. If you have a LOT of texts, especially MMS, saved on the phone this can help.
Delete or move photos, videos, documents, etc out of internal storage to SD, cloud storage or a computer.
Uninstall app updates.
Uninstall apps you have downloaded and installed. This is where you will have to decide what goes and what stays.