Censored delivery notification

[Ivan Dolezal]

Hello,

My users love when they can receive forwards of their mail as cellphone
SMS or pagers.
It's easy: Name.Surname:  name na machine, +420600123456 na sms.telco.cz

However when SMS/e-mail gateway crashes and loses all information (what
is, unfortunately, pretty common these days), an e-mail sender gets a
message like

While talking to sms.telco.cz:
<< +420600123456 na sms.telco.cz (expanded from Name.Surname) ... 550 User
unknown

This is an evident corruption of privacy, because this reveals a user's
cellphone number to a sender, so I'd need Sendmail 8.11.1 to answer
something like:

While talking to sms.telco.cz:
<< CENSORED na sms.telco.cz (expanded from Name.Surname) ... 550 User
unknown

Is there any better way to do it than hacking
sendmail/savemail.c:errbody with something like
anonymize(q->q_paddr) , where anonymize is my own char* function doing
the dirty job?

Or any other ideas?

Thanks in advance,

Ivan