Contact sender via Postfix Mailer-Daemon on "Bad recipient address syntax"

Question

I would like Postfix to generate and contact via Mailer-Daemon the sender recipient when the following case occurs Bad recipient address syntax.

I've been reading through Postfix docs but haven't found the right directive, any advice please?

Transcript of session follows.

 Out: 220 mail.mydomain.es ESMTP Postfix
 In:  EHLO mail.mydomain.es
 Out: 250-mail.mydomain.es
 Out: 250-PIPELINING
 Out: 250-SIZE 10240000
 Out: 250-ETRN
 Out: 250-AUTH PLAIN LOGIN CRAM-MD5 DIGEST-MD5
 Out: 250-ENHANCEDSTATUSCODES
 Out: 250-8BITMIME
 Out: 250 DSN
 In:  AUTH LOGIN
 Out: 334 VXNlcm5hbWU6
 In:  a2FpLm5pZWh1ZXNAY3YtY29hY2guY29t
 Out: 334 UGFzc3dvcmQ6
 In:  YmFyY2Vsb25hY3Zjb2FjaA==
 Out: 235 2.7.0 Authentication successful
 In:  MAIL FROM:<client1@client1-domain.com>
 Out: 250 2.1.0 Ok
 In:  RCPT TO:<rcpt1@whu.edu>
 Out: 250 2.1.5 Ok
 In:  RCPT TO:<"Foo - Bar <client2@client2-domain.com>FooBar FB">
 Out: 501 5.1.3 Bad recipient address syntax
 In:  RSET
 Out: 250 2.0.0 Ok
 In:  QUIT
 Out: 221 2.0.0 Bye

Answer 1

The sending client should handle this case. Postfix should not accept the message for the invalid recipient. From the dialog you have included it is behaving correctly. It is the responsibility of the sending software to provide the appropriate notifications.

If it has accepted the message, the sender may be fake so you do not want to send a bounce message. If you do send a bounce message after the message has been accepted. Sending such backscatter spam is bad practice, and may reduce the reputation of your server. Servers that receive backscatter spam may refuse your mail or assign it to the spam box.