Hello,

I ahave installed a new exchange server 2013 and i have noted the fowlloing two issues

a) Emails with attachement cannot be received from the server, the email is not received neither an error is sending to the sender.
Internally i can send email with attachments to local recipients
b) when i send messages from outlook 2013 all the emails are charactirzied by spam from the receipient, but when i send the same email from owa there is no problem. 

Please advise

Hello

a): check email flow wit Get-MessageTrackingLog -sender .... |fl
b): check message header for scl score

Hi,

As additional, I want to double confirm whether external user cannot receive message send from your environment and contain attachment, or cannot send message with attachment for external mail flow.

If its the former, it means mail flow works fine in your environment. You can contact administrator for destination forest to check attachment filter and transport rule.
If its the latter, this issue may be caused in your own configuration. We can check anti-spam filter, transport rule and send connector, run message track log and protocol log to find out the node for this issue.
More details about Anti-Spam and Antivirus Mail Flow, for your reference: https://technet.microsoft.com/en-us/library/aa997242(v=exchg.141).aspx

Thanks