Thanks Ray - I've done that and get a load of code, with the following in bold.
Could not instantiate mail function.
" ["BodyFile"]=> string(38) "../../webassist/email/Rotary/cttee.php" ["BodyFormat"]=> string(0) "" ["BodyText"]=> string(0) "" ["BurstSize"]=> string(3) "200" ["BurstTime"]=> string(1) "1" ["CC"]=> array(0) { } ["CharSet"]=> string(5) "UTF-8" ["Debugoutput"]=> string(4) "html" ["EmailsSent"]=> int(1) ["Error"]=> bool(true) ["ErrorMessage"]=> string(60) "Could not instantiate mail function.
I've looked up the error message and all the email addresses are valid.
Chris