E-mails through Squid3.0 problems

["Adam@Gmail" <adbasque@xxxxxxxxxxxxxx>]

Hello All,

I am having a serious problem with my E-mail programmes, none of my e-mails 
are going out
If I send e-mail from my website, they are not delivered as they used to
Confirmation, Subscription emails etc.. are not delivered

Is there anything that needs doing in order to allow those emails to go out
most of them are "php mailer" but there are others sent with sendmail 
system.

Any ideas please, this is very urgent and important more important than 
anything else so far
Regards
Adam