Outlook 2003; Why do I still get 0x800CCC78 error 530

[Guest]

I am unable to send email from Outlook 2003, I receive 0x800CCC78 errors
every time even though I have switched SMTP authentication on.
For some reason I have three accounts defined for my email address and have
manually set the SMTP authentication on for each account, I have also tried
the automated approach available from my ISP (BT Yahoo); but I still get the
problem.
I have looked through all recent relevant threads on this site but I seem to
have tried everything. When I tried to 'tick' SSL, the number in the box
changed from 587 to 25 and I then got error 0x800CCC7D (your outgoing server
does not support SSL-secured connections), so I reversed out this change.
The three accounts I have are all POP/SMTP and are 'mail.btinternet.com',
'127.0.0.1' & 'mail.btinternet.com(1)'.
All three had 'mail.btinternet.com' defined as its SMTP server.
For the POP3 server, 'mail.btinternet.com' account had 'mail.btinternet.com'
defined and the other two had '127.0.0.1' as their POP3 server. I changed all
three to have 'mail.btinternet.com' as the POP3 server and it got rid of a
0x800CCC0F message I was getting on receiving email - although I don't know
if I should have done this.
I thought of deleting all the accounts and defining one from scratch, or of
uninstalling Outlook 2003 and re-installing it, but I'm not technical and
don't want to lose all my emails.
I would really appreciate help with this as my ISP email system is driving
me nuts!
Thank you,

 

[Guest]

p.s. I don't know it it is relevant but I am using Norton 360. I was using
McAfee but I was having problems on that as well.

 

[Guest]

I re-installed Outlook and that sorted out the problem.