Hi jdo,
Thanks for taking the time to reply. I'll try to address each of your questions in turn, my answers are in bold italic.
We apologize for the confusion. The section to disable "Auto-Play Videos and Live Photos" is under Settings > Photos. That's okay. I didn't know whether it was a slip at your end or that the setting should have been in the place given in the post and my phone/iOS was odd for some reason. The post did ,however, help me to do an appropriate Google search to find out where that particular setting was- so it was all good in the end.
Regarding the "Swoosh" sound, the information below will help us more.
-When selecting another sound in Settings, did it play? Yes
Did you leave set to that sound long enough to determine if it worked when sending emails? No. I obviously need to test this.
-During the time that you do not hear the "Swoosh" sound, is the Ringer/Switch button in silent mode? No
Having it in silent mode will affect sounds such as sending emails.
-Do you have multiple email accounts set up? If so, does it happen with all of them? I do, but generally only use one which is exhibiting the 'no swoosh' issue. The 'no swoosh' appears to be when an email contains pictures and not when it doesn't (meaning ordinary emails make the 'swoosh' sound).
-Does the message send right away or does it move to the outbox and take a few minutes to send. If it takes some time, you may not get the Swoosh sound. Sometimes emails go straight away with the 'swoosh' sound but often (almost every time in fact) emails containing pictures go to the outbox first. Sometimes these emails will then go from the outbox automatically, more often than not, I have to resend them from the outbox [As an aside, this is rather annoying - is there any way of 'fixing' this so that it doesn't happen?]
RB