In Progress CPANEL-36285 - Change in forwarder behaviour?

4u123

Well-Known Member
PartnerNOC
Jan 2, 2006
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Hi, A client has recently reported an issue whereby forwarded Emails sent to several recipients that forward to the same mailbox are resulting in only one copy in the destination. Here's a simple explanation...

Scenario...

[email protected]
[email protected]
[email protected]

All three of these addresses forward to [email protected]

Until recently an Email sent to all three recipients would result in three Emails being sent to [email protected] - so three messages would arrive in the inbox - however, the client says recently this behaviour has changed - and an Email sent to all three recipients results in only one message being saved in the [email protected] mailbox.

I'm not familiar with how the forwarder functionality has worked in the past, so I can't claim that this is the way it has always been. What I'm trying to determine is whether this is something that has changed within cpanel recently and to clarify exactly how this is handled within cpanel.

We have mailscanner installed, so I don't know if this could potentially be a factor. I know that was updated recently.

Any advice you can offer would be very welcome.
 
Last edited:

4u123

Well-Known Member
PartnerNOC
Jan 2, 2006
938
21
168
Hi Rex, so can you please confirm that the intended behaviour of the cpanel forwarders would be as follows...

A single message sent to multiple recipients, each with a forwarder to the same account should result in multiple copies of the same message appearing in the destination mailbox.
 

4u123

Well-Known Member
PartnerNOC
Jan 2, 2006
938
21
168
Ok I've tested this with Mailscanner enabled and with it disabled. Each time, the target mailbox for the forwarders receives only one copy of the message.

As you can see, this message was sent from [email protected] to [email protected] [email protected] and [email protected]. Each of those has a forwarder to [email protected] but only one message was delivered there.

Note that SRS is enabled.

2021-03-18 09:06:48 1lMocC-0000UN-Kv H=myserver.myserver.net [x.x.x.x]:42114 Warning: Message has been scanned: no virus or other harmful content was found

2021-03-18 09:06:48 1lMocC-0000UN-Kv <= [email protected] H=myserver.myserver.net [x.x.x.x]:42114 P=esmtps X=TLS1.2:ECDHE-RSA-AES256-GCM-SHA384:256 CV=no S=6872 id=[email protected] T="Fwd: Fwd: Test Email, please ignore" for [email protected] [email protected] [email protected]

2021-03-18 09:06:48 cwd=/var/spool/exim 3 args: /usr/sbin/exim -Mc 1lMocC-0000UN-Kv

2021-03-18 09:06:48 1lMocC-0000UN-Kv => info <[email protected]> R=virtual_user T=dovecot_virtual_delivery C="250 2.0.0 <[email protected]> gKVDLSgYU2BtbQAAdcpwUA Saved"

2021-03-18 09:06:48 1lMocC-0000UN-Kv -> group ([email protected]) <[email protected]> SRS=<SRS0=O2YP+c=IQ=domain1.com=[email protected]> R=virtual_user T=dovecot_virtual_delivery C="250 2.0.0 <[email protected]> gKVDLSgYU2BtbQAAdcpwUA:2 Saved"

2021-03-18 09:06:48 1lMocC-0000UN-Kv -> marie <[email protected]> R=virtual_user T=dovecot_virtual_delivery C="250 2.0.0 <[email protected]> gKVDLSgYU2BtbQAAdcpwUA:3 Saved"

2021-03-18 09:06:48 1lMocC-0000UN-Kv -> nicole <[email protected]> R=virtual_user T=dovecot_virtual_delivery C="250 2.0.0 <[email protected]> gKVDLSgYU2BtbQAAdcpwUA:4 Saved"

2021-03-18 09:06:49 1lMocC-0000UN-Kv => |/usr/local/cpanel/bin/autorespond [email protected] /home/username/.autorespond ([email protected]) <[email protected]> SRS=<SRS0=O2YP+c=IQ=domain1.com=[email protected]> R=virtual_aliases_nostar T=cagefs_virtual_address_pipe

2021-03-18 09:06:49 1lMocC-0000UN-Kv Completed
 

cPRex

Jurassic Moderator
Staff member
Oct 19, 2014
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Root Administrator
Thanks for the clear details :D I tested this on my end and confirmed this behavior on my end, so I have created case CPANEL-36285 with our developers so they can look into this. I'll be sure to update this case with any additional information as I get updates.
 

4u123

Well-Known Member
PartnerNOC
Jan 2, 2006
938
21
168
Thanks Rex. I've looked through the logs for the last month and I've been unable to find a single instance of the message being received multiple times into the [email protected] mailbox, leading me to believe the client is wrong about how this may have worked previously.

If your internal case proves that the single copy is the intended behaviour and this hasn't changed recently, I'd be fine with that.

It does seem logical to forward only one copy of the message. Would like to know conclusively.