Reading email on Gmail app

[longcove2]

Hi: I'm using the bog standard gmail that came with the Nexus 7 2013 tablet. I'm running Android 5.0.2 version.
In this app the message is restricted to the right half of the screen and I cannot view full screen. I see even less if I expand the list on the left. Is there any way to read emails full screen?
I use K-9 for my important emailing accounts but I can't get gmail to work on it. Always refuses my name and password, yet they and server settings are correct.
Are there any apps other than gmail which works with gmail?
H'mm, I think that is three questions.
Thanks.
Donald

[Smelter]

There is also a similar problem with a Virgin media account. The "yellow folder icon" Email app no longer works. Gmail is the only 'working' mail app yet it failed to load the existing mail I had on my tablet, and fails to collect it. Android Chrome stopped working with Virgin media's web mail some time ago, which is ironic as Windows Chrome does work and shows a redirect to Google who manage the Email side of Virgins accounts. 

[S.Prime]

Boxer, will show your selected email full screen. This is the link:

https://play.google.com/store/apps/details?id=com.boxer.email



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