Urgent - emails blocked

[sianRCTCBC]

We have www.fosteringrct.co.uk hosted via joomla and this is a site that has an online "contact us" form for people wishing to have more information about becoming a foster carer for Rhondda Cynon Taf Council.

the form automatically sends the emails to [email protected] the council's email system.
for some reason, over the last two weeks, the council's spam filter has rejected a number of emails to this email address.
we have managed to recover the emails and the times and dates they were sent. However, the email addresses they come from do not make sense and our IT department have said there may be someone at Joomla who can help us unpick the source of the emails?
Thanks
sian

[sovainfo]

What component implements the "contact us" ?

[NickC4555]

Can you see exactly why the emails are being rejected? It could be because they cannot be verified as being sent from who they say they are coming from. Using an authenticated SMTP account instead of PHP Mail to send the emails might fix it. Adding an SPF record to the sending domain could also help.

[sianRCTCBC]

Thanks Nick

I am not sure why they were rejected other than they were spam. The email addresses they have come from are all @rctcbc.gov.uk email addresses but the user names (eg [email protected], which is one of the emails) are not actual @rctcbc email addresses, they are not anyone who works for the council. very odd.

[NickC4555]

But if you look in the email header, has it really come from that domain? I think that is your problem. Using an SMTP account will fix that.

[RedEye]

As Nick wrote, use your smtp account for sending mails!
You should never ever use PHPs mail() function on live sites, especially not if you don't know how it works.
Also that problem doesn't has anything to do with Joomla (at least in 99% of all those questions), just mail settings and your IT department really should know that...

[mandville]

but the user names (eg [email protected], which is one of the emails) are not actual @rctcbc email addresses, they are not anyone who works.

this is a clear sign of email spoofing https://en.wikipedia.org/wiki/Email_spoofing or https://en.wikipedia.org/wiki/Joe_job
if you get a lot of bounces then it can flag your entire domain as spam unless you use SPF records

on checking your site you show the email in plain, an easy for spammers to get official sounding email spoofers. try changing your form for a better looking one, and enable the email authentication.