I have a strange issue that I can't figure out. A hosted site sends out an email to a number of users. A few of their addresses are invalid or mailboxes are full, so the server tries to send a "Mail delivery failed: returning message to sender" message back to the sender. But these notices back to the sender get "frozen" in the queue because they have trouble being delivered. Eventually they disappear from the queue, but I don't see them listed in the delivery report history, so I'm not sure if they get delivered or dumped.
The strange part is that the rejection notices fail to be delivered back to the sender (with a valid address) due to a strange error.
When I try to force delivery of the reject notice back to the sender, it looks like there is an initial error due to some type of unencrypted communcation during the first attempt to connect:
Then it appears to try again...
So, it seems like there are two problems here:
1) The first attempt has some issue based on the message: "unsupported protocol: delivering unencrypted to H=mx.[snipped].com [snipped IP] (not in hosts_require_tls)"
2) The second attempt is really the one that confuses me: "SMTP error from remote mail server after MAIL FROM:<> SIZE=5104: 550 <> Sender rejected."
I'd appreciate any advice on #1, but I'm really curious as to why the receiving server is rejecting the message in #2 based on "MAIL FROM:<>" / "<> Sender rejected." When I view the rejection notice sitting the queue and click the icon to view the message details, it shows the FROM: header as
So wouldn't that be a valid non-blank sender? Yet, during the delivery attempt, the SMTP FROM line is sent as: MAIL FROM:<> SIZE=5104, and the error returned from that server is 550 <> Sender rejected. Why does my server not send over a FROM address, or if it does, why does the receiving server not recognize it?
Thanks in advance for any clarification or advice anyone can provide!
The strange part is that the rejection notices fail to be delivered back to the sender (with a valid address) due to a strange error.
When I try to force delivery of the reject notice back to the sender, it looks like there is an initial error due to some type of unencrypted communcation during the first attempt to connect:
Code:
LOG: MAIN
cwd=/usr/local/cpanel/whostmgr/docroot 4 args: /usr/sbin/exim -v -M 1jjDVI-0003eH-P0
delivering 1jjDVI-0003eH-P0
LOG: MAIN
Unfrozen by forced delivery
LOG: MAIN
Sender identification U=mailnull D=-system- S=mailnull
Connecting to mx.[snipped].com [snipped IP]:25 ... connected
SMTP<< 220 bosimpinc12 bizsmtp ESMTP server ready
SMTP>> EHLO [snipped]
SMTP<< 250-bosimpinc12 hello [snipped], pleased to meet you
250-HELP
250-SIZE 30000000
250-8BITMIME
250-STARTTLS
250 OK
SMTP>> STARTTLS
SMTP<< 220 Ready to start TLS
SMTP(close)>>
LOG: MAIN
TLS session: (SSL_connect): error:14077102:SSL routines:SSL23_GET_SERVER_HELLO:unsupported protocol: delivering unencrypted to H=mx.[snipped].com [snipped IP] (not in hosts_require_tls)
Transport port=25 replaced by host-specific port=25
Code:
Connecting to mx.[snipped].com [snipped IP]:25 ... connected
SMTP<< 220 bosimpinc12 bizsmtp ESMTP server ready
SMTP>> EHLO [snipped].com
SMTP<< 250-bosimpinc12 hello [snipped IP], pleased to meet you
250-HELP
250-SIZE 30000000
250-8BITMIME
250-STARTTLS
250 OK
SMTP>> MAIL FROM:<> SIZE=5104
SMTP<< 550 <> Sender rejected.
SMTP>> QUIT
SMTP(close)>>
LOG: MAIN
** [snipped]@[snipped].com R=dkim_lookuphost T=dkim_remote_smtp H=mx.[snipped].com[snipped IP]: SMTP error from remote mail server after MAIL FROM:<> SIZE=5104: 550 <> Sender rejected.
LOG: MAIN
Frozen (delivery error message)
1) The first attempt has some issue based on the message: "unsupported protocol: delivering unencrypted to H=mx.[snipped].com [snipped IP] (not in hosts_require_tls)"
2) The second attempt is really the one that confuses me: "SMTP error from remote mail server after MAIL FROM:<> SIZE=5104: 550 <> Sender rejected."
I'd appreciate any advice on #1, but I'm really curious as to why the receiving server is rejecting the message in #2 based on "MAIL FROM:<>" / "<> Sender rejected." When I view the rejection notice sitting the queue and click the icon to view the message details, it shows the FROM: header as
Code:
From: Mail Delivery System <[email protected][my server hostname].com>
Thanks in advance for any clarification or advice anyone can provide!