Big problem with mails

[Seven77]

Any help for this:

Today all of our clients (almost) called and told us that they can't send mails out.

The get following message:

Host xxx.xxx.xxx.xxx is not permitted to relay through server.xxxxxx.xxx.
Perhahps you have not logged into the pop/imap server the last 30 minutes.
You may also have been rejected because your ip addr.


We did not change anything - we only made the recommended security update.

Any help would be great!
Thanks!!

Seven

 

[SHSaeed]

I'm guessing this is when they try to use your server as SMTP server for outgoing mail. Tell your clients to set their email clients to use &POP Before SMTP& authentication. It's a security feature to stop people that do not have an email account from using your server to send out email (mainly SPAM).