Message delivery failed

Some staff try to send email to a group of recipient, but failed and got the following error message

"The server has tried to deliver this message, without success, and has stopped trying. Please try sending this message again. If the problem continues, contact your helpdesk".

We use a SBS, exchange server in our office, connected via pop3 connector to an email service provider.

can anyone help me?

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Sumit GuptaSystem and Virtualization EngineerCommented:
Try restarting the tranport service.. sometimes it just start working by that..
Patrick BogersDatacenter platform engineer LindowsCommented:
Hi Far,

First thing to try is to restart your transport service.
If this is not working, what version OS/exchange are you using?
Nick RhodeIT DirectorCommented:
Are they sending it to the correct address?  Like they are typing in the group as vs  Usually its a mistype which might be cached
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How many addressees in the group?  Probably exceeding the number of connections configured for the exchange.  the Pop connector is only for checking pop accounts how is the server configured to send email? Is it forwarding to your ISP email or routing via dns, if forwarding that server may also have a limit on connections per email, typically I think this is around 25 recipients.
far55Author Commented:
The staff was sending to up to 30 recipients.

By restarting the transport service, you mean the hub transport service?

We are running Exchange server 2010. We forward emails to our ISP email. Please can you explain which server limit are you talking about. My server or ISP?
Patrick BogersDatacenter platform engineer LindowsCommented:

Have a look here, it is about max recipients in Exchange 2010. link.

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far55Author Commented:
thanks i checked and increased the sizes of  the recipients and everything seems ok. but i will have to monitor it.
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