I have had help from another source and it would appear that these strange symbols are Smart Quotes and a .....nuisance! It is possible to correct them whilst typing, but what a fuss. The problem occurs when typing either an apostrophe or quotation marks. However by backspacing immediately after the type - and notice the small change in the shape of these characters on the screen - the recipient gets a proper punctuation mark.
Andy Rathbone, author of some of the Dummies books has helped me in this respect and is trying to find a permanent way to stop it from happening. I am also trying to make contact with Microsoft on this issue.