Specify the envelope From: address to associate with a message. The item_address and item_length fields specify the address and length of a text string containing the envelope From: address to use for the message submission. The length of the string may not exceed ALFA_SIZE bytes. Only one envelope From: address may be specified.
The MTA_ENV_FROM action should be used when the envelope From: address is not a local address. When the address is a local address, then only the user name should be specified using the MTA_USER action.
If this action and the MTA_USER actions are not specified, then the user name associated with the current process will be used.
Do not use this item code in conjunction with the MTA_USER or MTA_SUB_USER item codes.