Hyperlinks arrive as plain text!

AquaMail did the trick. I was successfully able to send a link to a PC. The link arrived functional. So evidently the stock e-mail app on the Galaxy S5 is poorly engineered; I say this because AT&T had updated my Android OS and all the apps. I'm surprised Google (or is it AT&T?) bundles unstable software. While I prefer what I regard as a more logical GUI of the stock Email client, I will stick with the functional AquaMail. My...it has so many features, most of which are for advanced users.

Thanks again for your kind patience.

When the warranty of the S5 expires, do you recommend rooting the device?
 
When the warranty of the S5 expires, do you recommend rooting the device?
My LG G4 is the first smart phone I have owned. Except for the possibility of uninstalling the bloatware, I have yet to find a need for rooting the phone. YMMV.
 
I'm surprised Google (or is it AT&T?) bundles unstable software

The stock email app is from Samsung, not Google. It's certainly possible that the recent system update might have introduced a bug in the Email app, since that's the only way the app can be updated (it's not on Google Play Store or Galaxy Apps Store). A bug like this could be due to a couple of possibilities: (a) something went wrong with the update process, introducing some glitches, or (b) the update itself that was pushed by AT&T included a bug. It's probably not worth it at this time, but one thing you could try is to reinstall the firmware using Smart Switch: SmartSwitch: Install & update or replace firmware. If the bug happened because of a problem with the update process, then this could potentially fix it.