What app are you using for email?
Clear the cache in the email app.
Go to settings, apps, and find the email app in that list. Choose storage, clear cache. Reboot

 

What is the email provider that's not downloading?
Such as
Outlook?
Yahoo?
Gmail?
It just might be that their server is down...

 

Is it possible you changed your password in your email account, and now need to change it for the settings for that email account on your phone? This has been my issue in the past....

 

Have you tried logging into your e-mail with your browser?

Although this won't (probably) solve this issue, it WILL allow you to use your e-mail.

 

Oh this issue annoys me very often. And I have some solution.
1.(Unknown Reason) -->As Dannydet said, clear the cache and the user data of the mail app. And... if possible, reinstall the app.-
2.(Sync is not enabled) -->Maybe it's caused by power saving apps, Just re-open it from settings.
3.(Mail sync process not enabled) -->Try to check "Settings>Accounts>ur account>enable the mail sync stuff"
4.(Storage is almost full) -->Well... That's gonna be tricky. Clean up your phone for some space or your phone won't enable the sync process.
5.(Unverified Account) --> As Michelle_2112 said, u can try to login again or something else...
6.(Technical difficulties) --> Yeah... as puppykickr said, just try to login from your browser even it's a little bit annoying sometimes..
Hope it's work

 

OK, good.
We have narrowe it down to G-Mail.

That means that I might be of some help here.

Go back to your apps list inside settings, and locate the G-Mail app.
Clear all data.

This will only reset the app, not your account.

To prevent future confusion, also find that other E-Mail app {probably an icon with a yellow enelope and an open flap} and clear all data and then disable it if you are permitted to do so.
{This is a stock e-mail app, and if you are using G-Mail, you are not using this app.}

Also see if you can find, delete data, then disable {if available} Exchange Services.
If G-Mail is your only e-mail, then you most likely will not be needing this one either.

Back to the issue at hand, open Google Play Store, and turn auto-update OFF.
This 'feature' from Google is much more of a pestilence than it is anything else.

Remember that eventually, all active apps eventually will receive an update that:
A. Makes the app into something you no longer wish to use.
B. Causes the app to have bugs that cause malfunction or total failure.
C. Makes the app incompatible with the device.
D. Any or all of the above.

Worse yet, Google has the most annoying habit of doing such updates at 2:30 A.M., so that a working app at bedtime can be a nonfuctioning headache when you wake up {as you have found out}.

I cannot tell you how many times I have woken up to a completely different device than what was there when I fell asleep.

There is an od saying that goes something like, "Never update software that is working."

See the real kick in the dumper is that if Google updates an app with some new version that has problems {happens all the time}, there is no way via Google {unless you want to try with a computer} for you to get the older, working version back again.

So, what to do?

First, open your G-Mai app and log in.
You will now have the original app as it was when you irst got the device.
You will need to go through the settings, and redo them to your liking.

Does it work?
If so, good. If you like the results, you can stop here.
If not, then continue on.
Of course, you may continue on if you want a bit more information as to how Google works.

Another possible issue is your Google Drive account.
Google gives you 15 GB of free space on their servers.
Cool, right?

Well sure.
Free online storage IS pretty cool most of the time.

What is not well understood by most is that everything that you do with G-Mail is stored in this 15 GB.

Do you use Google Photos to back up your media?
Well, unless you pay money for more space, Google uses some of that 15 GB of space.

Spam, trash, inbox, outbox, all those e-mails that you thought that you had deleted?
Guess what? Nothing gets truely deleted for 30 days, and even then we have to take Google's word for it.

So, if your Google Drive is full, then it will be not able to work right for your e-mail.

To be honest, I get so much crap in my inbox that I basically gave up on putting anything of any real value of my own on Google Drive.
Because there is no 'Delete All' function with G-Mail, I have spen days the last two years just cleaning out stupid e-mails.

Yeah, this year?
I said to **** with that.
More hassle than it is worth.
It just fills right back up again.

I am actualy anxious to empty my Drive accont of everything vauable, and then disable the app.
All the annoying warnings about it being full make the app more of a pestilence than the 15 GB will ever be worth.

Anyway, let's hope that these methods work for you.

When you are wondering if your apps have pending updates, what do you do now?
Well, you could open Google Play Store and then tap the hamburger menu in the top left, then select My Apps.

My problem with this is that it is still way too easy to tap somewhere that will cause an update to begin on apps that I do not want updated {I have more than 20 like that}.

At any rate, what you should do is tap the app itself, to bring up that app's page in Google Play.
Here, before you choose to update, you can read recent comments- and see if other people ar having problem since they updated.
Many, many times before I have seen Google update something, and hundreds of people will take the time to leave a bad review.

Google being Google, of course, will often delete bad reviews almost as soon as they appear, but you usually can get some kind of idea as to how the lates update has gone over.

But keep in mind that the version of the app that came with your device should function just fine.
My devices are all older than yours {and so use an even older version of G-Mail than yours}.

A better option in my experience has been to install UpToDown, which is the number two appstore worldwide.
This appstore is simple to control, and not intrusive {like Google}.

Much like the Play Store, it will scan your device and see if updates for your apps are available.
Unlike the Play Store, however, older versions of apps are readily available.

To be fair, I do not use UpToDown to download updates for any Google company apps {Play Store, G-Mail, Drive, Play Games, Play Services, etc.} because sometimes beta versions are made available here before they are actually ready to be released.
{No problem with non-Google apps, however.}

But you can let it scan the device to see if update{s} are indeed available.
Then you can check te recent reviews on Play Store and see if you want to risk it.

I have been using UpToDown for years, and like it much better than Google Play Store.
It even updates apps faster than Play Store!

{website}
https://en.uptodown.com/

{app page}
https://uptodown-android.en.uptodown.com/android

 

Google has been having massive problems with their Android System Webview app recently.

It has affected many, if not most Google apps.

The first thing to do is to open up the Play Store and make sure that you have the most recent update of Android System Webview.

Then be sure that G-Mail is not in your recent apps, and restart the app from your appdrawer, or the icon on your homescreen if you do it that way.

Pull down from the top, and it should begin to refresh.

If this does not help, then make sure that your Sync setting is on.

You can also go into your device settings, find Accounts, and verify the sync there.

Stil not working?
Then go through the settings within the G-Mail app.
Somewhere in there is the controls for how much e-mail is brought in when you open the app.

If all else fails, you can always use your browser on the device to access the G-Mail site.