We have an in-house application that is generating email with attachment. This email is relayed through our Exchange 2010 to two mailboxes. One mailbox is located on this exchange server, 2nd mailbox is located at the customer place. Email is received correctly in the first mailbox (our relay server), but the customer receives corrupted attachment. But, when we forward the same email from our mailbox then the customer receives perfectly good copy.
Any idea where to look and what to change? I'm currently out of ideas. It seems like exchange relay does something with the message encoding and not all clients are able to work with it correctly.