I have a process that sends emails to the Contacts of a set of Accounts (customer notification).  To do this, I create the message for each Account, as it is customized for the Account.  Because of the governer limit of 10 on invoking email send, I accumulate these in an array, then send at once. 

Unfortunately, if any of the emails are on a bounce list, then it fails to send any of them.  At any given time you are likely to one or more customer emails bounce, so this is very impractical.  Moreover, although I notify the requester of the exception, it does not include the email address that bounced, so is hard for an end-user to remedy:

First exception on row 1; first error: INVALID_EMAIL_ADDRESS, email address has bounced for id : 0037000000RqE7e: []

Even if I parse and discover the email address of the contact, there are reasons why an end-user cannot necessarily correct the situation, such as the customer's email server is temporarily unavailable.  

How does this conflict with the governer guidelines?  If there wasn't a limit of 10 send requests per HTTP request, I'd send each email individually, permitting all the others to successfully be sent despite the failure.