extra <> around source-route MAILER-DAEMON messages?

[Bob Cunningham <bob@soest.hawaii.edu>]

In messages bounced back from some (sendmail?) MAILER-DAEMONs, zmailer
often objects to envelope and/or "To:" header syntax errors like the
following (this is just one example):

>Error in "to" envelope address:
>
>	<@kahala.soest.hawaii.edu:aar< @GFDL.GOV>
>				     ^-illegal end of route address, illegal end of route address, missing end of address
>
>
>Error in "To" header address:
>
>	<@kahala.soest.hawaii.edu:aar< @GFDL.GOV>
>				     ^-illegal end of route address, illegal end of route address, missing end of address
>

I can understand the obvious problem with a "To:" address like this,
tho I'm not exactly sure how it might come to be generated somewhere:

>To: <@kahala.soest.hawaii.edu:aar<@GFDL.GOV>

But the envelope is even more puzzling.  Shouldn't zmailer simply be
defocusing this by stripping the gratuitious extra enclosing <> marks?

>   ----- Transcript of session follows -----
>554 <<@kahala.soest.hawaii.edu:aar@GFDL.GOV>>... Unbalanced '<'


Any helpful insight or advice?


Bob Cunningham
bob@soest.hawaii.edu