David wrote:
> > One possible approach is to appear to accept all addresses, then > > check the recipient address but take no action until the DATA phase > > - at which point you can refuse the message with a 5xx error without > > indicating whether the address exists or not. > > That doesn't work if there is more than one recipient, some > valid and someinvalid. At the end of DATA, you can only indicate success > or failure for the entire message and all recipients. Bouncing the message for all recipients if one of the recipients is invalid could be a valid approach, depending on the site policy. Alternatively, bouncing it if more than a small number (e.g. 2 or 3) are invalid would catch dictionary attacks without unduly impacting on messages with a typo in manually-added addresses. Best Wishes, Paul. __________________________________________________ Paul Murphy Head of Informatics Ionix Pharmaceuticals Ltd 418 Science Park, Cambridge, CB4 0PA Tel. 01223 433741 Fax. 01223 433788 _______________________________________________________________________ DISCLAIMER: This email and any files transmitted with it are confidential and intended solely for the use of the individual or entity to which they are addressed. If you have received this email in error please contact the sender or the Ionix IT Helpdesk on +44 (0) 1223 433741 _______________________________________________________________________
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