| Macro | § | Sets What |
| confFROM_HEADER | From: | Define the format for the From: header |
| confRECEIVED_HEADER | Received: | Define the format for the Received: header |
| confOLD_STYLE_HEADERS | OldStyleHeaders | Declare the OldStyleHeaders option |
| confMAX_HEADERS_LENGTH | MaxHeadersLength | Declare the MaxHeadersLength option |
| confMAX_MIME_HEADER_LENGTH | MaxMimeHeaderLength | Declare the MaxMimeHeaderLength option |
| confSINGLE_LINE_FROM_HEADER | SingleLineFromHeader | Declare the SingleLineFromHeader option |
| confUSE_ERRORS_TO | UseErrorsTo | Declare the UseErrorsTo option, which affects the Errors-To: header |
| confNO_RCPT_ACTION | NoRecipientAction | Declare the NoRecipientAction option, which affects the To: , Cc: , and Bcc: headers |
| confRRT_IMPLIES_DSN | RrtImpliesDsn | Declare the RrtImpliesDsn option, which affects the Return-Receipt-To: header |