SMTP authentication issues

[#1]

Hi Folks,
Although I'm only a phone customer with plusnet these days, I'm trying to keep the email account going because my wife uses her force9 mailbox as her sole account for sending & receiving email.
We switched ISPs on the 2nd of May and the email was still working fine at that point, the only change I had to make was to add username and password authentication for the SMTP server but it worked just fine.
Towards the end of May I started having serious problems: Somebody deleted my entire account by mistake, my phone was cut off, all our emails were lost and we had a nasty letter from PN credit control demanding payment. After a lengthy discussion with COT we eventually got the account traced and reinstated.
Since then the only issue that remains is that we can't send email via our Force9 mailboxes any more, we can only receive. Not such a problem for me since I have a gmail account but my wife is completely reliant on the Force9 account. I've phoned tech support who ensure me that the service is active and suggested I try setting it up again - no joy. I've tried from Mac OSX mail, outlook 2011, android and iOS, all receive but can't get it to send on any.
Please could anyone help me out with this? I've followed the web setup guides to the letter and as I mentioned the authentication was working before, so I don't understand how it could be a setup issue but I'm quite prepared to listen.
Stu

[#2]

I believe you need to have an active subscription Broadband account with PlusNet to be able to use smtp authentication. You need to use your new ISP's smtp server to send mail.

[#3]

Correct.

[#4]

Thanks for your replies. I think that policy is rather poor, considering I'm still a long term customer. I moved from BT to force9 about 7 years ago and the email account with BT still functions for both send and receive!
OK,  if I set my wife up with a gmail account, can she use that for sending but still give Force9 as a 'reply to ' address?
Thanks again for your help. 

[#5]

You should be able to leave everything as it is, except for changing the outgoing server to the smtp server that your new ISP provides.

[#6]

I think if you use gmail you may end up with emails being sent from "xxx@gmail.com on behalf of yyy@username.force9.net"

[#7]

That's right I think jelv unless you specify an smtp server of your own. In doing so it needs to support smtp auth and tls/ssl too IIRC which the OP wouldn't be able to.

[#8]

I had a nose round in gmail settings and it appears that you can integrate another email account. You can also use the other address as the default one to send from via the gmail server, showing the alternate address as the sender rather than the gmail one, which is exactly what I want, but I haven't tested this using an email client yet. I want to try and get it working through a client rather than relying on the web interface. I've created an account for her so I'll have a play later and let you know. If it doesn't work I still have the option of trying my old account on the BT Yahoo server as well. Last resort is to simply tell her she has to start migrating to gmail or BT Yahoo. 
Thanks again for your input.

[#9]

Working a treat now. Signed her up to gmail then reconfigured the outgoing server on her Force9 account to gmail smtp server, using gmail email and password for authentication. Now she can send email again and the recipient gets the same Force9 address to reply to.
Cheers