Some SMTP servers process message body and may reject message after message body transfer (after DATA command).  In RFC 821 following codes was declared for this situation:

552 Requested mail action aborted: exceeded storage allocation

554 Transaction failed

451 Requested action aborted: error in processing 

452 Requested action not taken: insufficient system storage

And all of this replies is not mean that there no chances to delivery message. And ADR will try deliver message again and again.  In version 1.42 registry DWORD variable DataBreakCode was added. This variable is not set by default. Low and high words of this variable contain SMTP server answer codes on which ADR will move message in “Bad” folder. Note, that this variable contain codes for DATA command only.

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