I am getting the following error whe I attempt to execute a query.
 

Line: 4, Column: 14
Didn't understand relationship 'attachment' in FROM part of query call. If you are attempting to use a custom relationship, be sure to append the '__r' after the custom relationship name. Please reference your WSDL or the describe call for the appropriate names.

The query (being executed via the debug in developer console

PUBLIC STRING strTemplate_Initial;
strTemplate_Initial = 'TEST EMAIL';

PUBLIC LIST <ci_mailout__c> objMailout;

objMailout = [SELECT m.Id, m.contact__c, contact__r.Name, m.recipient_first_name__c, m.recipient_last_name__c, caps__r.AccountID__c, m.file_password__c, m.email_address__c, (SELECT ID, Name, ContentType, body FROM attachment) FROM ci_mailout__c m WHERE Sent__c = FALSE AND Mailout_name__c = :strTemplate_Initial ORDER BY Policy_count__C Desc LIMIT 100];

SYSTEM.debug('Size of Mailout: ' + objMailout.size());

The code I originally had was two seperate queries on for the mailout and one for attachements which worked, however, it starts to hit the limit for SOQL statements and so I was thinking I could join the two statements to reduce the calls.

Original SOQL (in isolation)

objMailout = [SELECT Id, contact__c, contact__r.Name, recipient_first_name__c, recipient_last_name__c, caps__r.AccountID__c, file_password__c, email_address__c FROM ci_mailout__c WHERE Sent__c = FALSE AND Mailout_name__c = :strTemplate_Initial ORDER BY Policy_count__C Desc LIMIT 50];

objAttachment = [SELECT ID, Name, ContentType, body FROM attachment WHERE ParentId = :thisMailOut.Id];

Thanks for your help ...