Well that's been another interesting morning with the 123-Reg SMTP server.
Unfortunately, I did not have a saved example of my own code settings that I used for the 123-Reg connection in March earlier this year but I knew that your code looked familiar to my own code so I took your code example, incorporated my own credentials and sent an email.
Would you believe it? I got exactly that same result that I got in my previous trial and errors in March this year. That being, the code runs through it's defined logic correctly and no errors are returned from either the code or the SMTP server but no email ever appears at the defined recipients inbox?
I tried sending about a dozen emails over a period of an hour this morning and then sat here scratching my head wondering once again "what the heck is going on?" Just at that point "Ping" went my email and one of the elusive little buggers turned up in my inbox? Now that's even more weirder than what I experienced last time but what it did confirm was that the connection was being made to the server but something has to be stopping it getting through?
I then went searching again on the 123-Reg site for answers and, lo and behold, I found this. This was definitely not there in March, or if it was I missed it:-
This gives a few other ports that can be used for the SMTP server if it is found that emails are being "blocked". It just so happens that Gmail uses port 587 so I tried that instead of port 25 and would you believe it:-
Everything works perfectly! Thank god and at last.
I am certain that this has been at change at 123-Reg in the last 6 months so this may be something you want to remember in case you start to get issues with port 25.
Finally, I would just like to say a big Thank you for your help and willingness to post your own code for me to finally get up and running with 123-Reg.