FYI: we've had reports that there are issues with the latest release of the Samsung email client (6.0.01.11) sending messages when using EAS. I recently got a Samsung S10+ and verified a few things:

1. Using autodiscover works perfectly: it found my SmarterTools account and set it up with no issues as an EAS account. 

2. Shared calendars synced just fine.

3. Syncing between the phone, webmail and other clients is fast and has zero issues.

3. However, when trying to send an email, it just sits in the Outbox. 

Samsung is aware of this issue, and they're working on a fix. The BETA version of their email app apparently has a fix, but the patched version isn't available yet. A customer who reported this issue sent us a reply they received from Samsung Electronics Email Team that confirmed they are aware of the issue and that it is in the process of being resolved. 

Their immediate solution is to downgrade to the previous release or contact them for access to the BETA of the new client. If you want to try the BETA, send your Google account info to them at b2b.sec@samsung.com. (And it goes without saying: your participation in their BETA is in no way endorsed, supported or otherwise authorized by SmarterTools, and participation is at your own risk.) We also verified that downgrading DOES work for sending email when using an EAS account, so that's our recommendation.