amavisd-new in proxy mode - D_REJECT causing senders to unsubscribe users?

[Tom Johnson]

We're running amavisd-new in the pre-queue proxy mode.

We had a user receive an email from an email service provider (SendGrid), and that exceeded the user's spam cutoff.

We're set to D_REJECT spam, but the user reports that SendGrid then disabled the user entirely, because they don't send messages to users that have hard-bounced.

Has anyone else seen this issue?  I'm surprised by it, and wasn't expecting this - was I just being naive?

Would it require the use of D_TEMPFAIL in this case? That seems unfriendly, but is that the solution?

Thanks-

Tom