Emails are not delivered to the particular recipient in Plesk: marked message to be discarded if not explicitly delivered (discard action)

Symptoms

• Emails are not delivered to the john.doe@example.com mailbox on a Plesk server from all or particular senders.

• The following message can be found in /var/log/maillog log file:

  CONFIG_TEXT: servername dovecot: service=lda, user=john.doe@example.com, ip=[]. sieve: msgid=20180923061540.Horde.zyLIfVJmZISHx3cXgJ9740t@webmail.example.com: marked message to be discarded if not explicitly delivered (discard action)

Cause

Custom Sieve rule is configured to discard a specific recipient mailbox.

The following configuration exists in the *.sieve file under /var/qmail/mailnames/example.com/john.doe/sieve/ directory:

CONFIG_TEXT: # Blacklisted Addresses
...
if address :all :comparator "i;ascii-casemap" :is ["From", "Sender", "Resent-From"] ["john.doe1@example.org", "john.doe@example.com"] {
discard;
stop;
}

CONFIG_TEXT: # rule:[.]
if true
{
discard;
}

Resolution

1. Login into Webmail.

2. Define the custom filtering Sieve rule:

   • For Roundcube: in Settings > Filters.
   • For Horde: in Mail > Filters menu.

3. Modify/remove the rule that blocks some or all senders.