Difficulties with SMF and Joomla sending mail from my CGI site

[#1]

I have created a website with Joomla content as well as an SMF discussion forum.
Unfortunately I have found it impossible to get either application to send e-mail. I've looked for answers in the various pus.net forums as well as the Joomla and SMF support pages. I get errors when I try to forward a Joomla article from the web site. Messages from SMF aren't sent out either,  despite no error being apparent to a user.
I've tried to use both plus.net SMTP relays as well as gmail relays.
Neither seems to work. I've modified the file permissions on various PHP files to 755 without any luck.
I've changed the sendmail options in Joomla to use SSL and used various settings for the smtp server, port 25, port 465, secure/insecure etc.
I've modified the sendmail path to /usr/sbin/sendmail -t as well as /usr/sbin/sendmail .
None of these seem to work. Does anybody have any experience of doing this on plus.net ?
I'd be very grateful for any help.

[#2]

OK finally got it to work.
These are the settings in Joomla.

Mailer	SendMail
Mail from	<My email address>
From Name	<My website name>
Sendmail path	/usr/sbin/sendmail
SMTP authentication	Yes
SMTP security	None
SMTP port	25
SMTP password	My PlusNet password
SMTP host	relay.plus.net

It took ages to prove this because mails can take several hours to arrive so trial and error is very time consuming.

[#3]

Weren't you also required to supply your Plusnet username for authentication purposes?
The delays to mail you mentioned might have been associated with the send and receive problems reported in Service Status over the last few days. Those are now fixed.
David