i had several iphone voice memos fail to email from the phone today, each no larger than 1mb (256kb .m4a file for example, just a little 10 second clip), with a strong wifi signal on iPhone 6 iOS version 10.3.1... try to send as "mail" from the voice memo app > "share" > "mail" > the file shows up as an attachment in my email app like expected, add recipient & hit send > i hear the 'woosh' sound as if it was sent, but come to find out hours later the emails never went... tried a few more times recently from the phone to email with the same failed result.. still not sure why.. eventually i messaged them from my phone to myself instead, voice memo > "share" > "message" > enter my own contact & send, then I opened the messages app on my computer, the messages had come through in less than a minute > then i downloaded the files from messages to my computer's local hard drive, then attached the downloaded files to a new email on my computer via gmail in web browser, and send, they went out fine right away... in this case pretty sure it is not an issue of file size or data speeds.. seems to be some type of glitch or bug with the phone or iOS itself regarding voice memos > mail... workaround is okay but not ideal if my computer wasnt handy.. i assume airdropping to my own computer might have been a viable workaround as well, but didn't try that... Voice Memos > share > Mail is not working as expected with my configuration, consistently fails. frustrating, disappointing