Email replies disappearing

[DisplayName9999]

Some of the emails which I reply to vanish into thin air. They are not unsent or in spam they just disappear.  This also randomly happens to forwarded emails from myself to others. In technical terms an intermittent fault.  There is no pattern in this.  These are commonly used email addresses . You can imagine the problems this can cause when I swear blind I have replied/ forwarded something only to find it has vanished . What is going on? BTW when I have picked up something hasn't gone I try again with copying myself and it still vanishes. The only solution is to cut and paste into a new mail and it will go. Any ideas?

[caesarome]

How are you accessing your emails, do you login to the Sky website or are you using a program or app like Outlook ?

[DisplayName9999]

Thanks for the reply. Email app Google play store.  

[caesarome]

And is your email account set up as a POP account or IMAP one ?

Do these emails show up here via your online account:

https://skyid.sky.com/signin/email/

[DisplayName9999]

Yes...not sure where to check for IMAP or POPS