[Users] January 19, 2021 Zeta Alliance Conference Call Summary

Daniel Eugenin deugenin at itlinux.cl
Mon Feb 1 20:38:26 CET 2021

Hi all!, about "max message size per domain", i have an approach modifying amavisMessageSizeLimit per account. 
Setting a general zimbraMtaMaxMessageSize, and a smaller value of amavisMessageSizeLimit per account. 

[ https://soporte.itlinux.cl/hc/es/articles/200120988-Limitando-message-size-por-cuenta | https://soporte.itlinux.cl/hc/es/articles/200120988-Limitando-message-size-por-cuenta ] 


Daniel Eugenin M. 
IT Linux 
[ https://www.itlinux.cl/ | www.itlinux.cl ] 

De: "Randy Leiker" <randy at skywaynetworks.com> 
Para: "users" <users at lists.zetalliance.org> 
Enviados: Viernes, 22 de Enero 2021 16:52:37 
Asunto: [Users] January 19, 2021 Zeta Alliance Conference Call Summary 

Hello Zeta Alliance Community, 

Here is a summary of this week’s conference call. A few brief reminders: 

    * Conference calls are every Tuesday and open to all using either the FreeConferenceCall.com VoIP app or via a dial-in number: [ https://www.freeconferencecall.com/wall/zetalliance | https://www.freeconferencecall.com/wall/zetalliance ] 
    * Each week’s call agenda can be found at: https://drive.google.com/drive/folders/1xDyBJFjnfZYxuXJHiDzsXjjMuGGtIl7J 
    * A copy of each week’s summary is also posted to the Zimbra Forums: 
        * All Prior Months: [ https://forums.zimbra.org/viewforum.php?f=9 | https://forums.zimbra.org/viewforum.php?f=9 ] 
        * December 2020 : [ https://forums.zimbra.org/viewtopic.php?f=9&t=69008 | https://forums.zimbra.org/viewtopic.php?f=9&t=69008 ] 
        * January 2021 : [ https://forums.zimbra.org/viewtopic.php?f=9&t=69121 | https://forums.zimbra.org/viewtopic.php?f=9&t=69121 ] 
    * Constructive feedback on these call summaries is always welcome. 

January 19 , 2021 

Setting A Maximum Message Size Per Domain 
Noah P. said that he is looking for a means to enforce a maximum email size limit per Zimbra domain. He explained that he has two customers that want to keep email messages within their organizations smaller than they are now, and Noah does not wish to apply the lower size limit to all other customer domains on his Zimbra servers, but rather just to those two customer’s domains. Cine suggested that CBPolicyd ( [ https://wiki.zimbra.com/wiki/How-to_for_cbpolicyd | https://wiki.zimbra.com/wiki/How-to_for_cbpolicyd ] ) might be of help, and said that he knows CBPolicyd can set a maximum outbound message size limit, but was not certain if it was possible to set an inbound message size limit too. Mark S. suggested that Noah could setup a new Zimbra MTA server specifically for the customers requesting the lower message size limit, then route all of the email for those two customers through the new MTA server. Matthew F. said that writing a Postfix Milter to filter based on message size might work, but the downside to this approach would be that messages that are too large would bounce to the sender only after Zimbra initially accepts the messages for delivery. Matthew also pointed out that in doing a quick Telnet connection test to his Zimbra MTA server, he noticed that Postfix advertises the maximum message size accepted immediately after the HELO/EHLO command is sent, suggesting that it may only be practical to have a server-wide message size limit set, as compared to a per domain setting, assuming that all of the users are using the same Zimbra MTA server. 

Resetting Mailbox Passwords When Two-Factor Authentication Is Enabled 
John E. shared an update on an issue discussed in an earlier Zeta Alliance call related to difficulties encountered when attempting to use the Zimbra password reset feature for a mailbox with two-factor authentication enabled. He said that this has been acknowledged by Zimbra as a bug (ZCS-10191; status updates are not available via the Zimbra Support Portal) and is anticipated to be fixed in an upcoming patch that should be released soon. Noah P. asked if the bug fix will only apply to the Modern UI, the Classic UI, or both in Zimbra 9. John E. said that the bug fix is associated with the server back-end, so he thinks it should apply to both the Modern and Classic UIs. 

Using Shared Calendars Containing The Same Calendar Event UIDs 
>From the Zeta Alliance mailing list, Frederic N. said that he has Zimbra users who have multiple shared calendars, and they often add the same calendar events to these multiple shared calendars with the same UID number. His users report that when their email clients are configured to synchronize each of these shared calendars, they expect the calendar events with the same UID number to appear for each shared calendar, but the actual behavior observed is that the calendar events appear only once on a single shared calendar – usually the shared calendar that synchronizes first. He wondered if this occurs because of the de-duplication feature in Zimbra that also avoids repeatedly delivering email messages with the same message ID number. Cine said that Frederic did not mention which email clients are in use by the users, but generally it is up to each email client to decide on which calendar events they will download, rather than the Zimbra server. He did not think that the de-duplication feature in Zimbra was involved, as that feature only applies to email deliveries. John H. added that most email clients will consider calendar events with the same UID to be the same calendar event, thereby causing the event to be displayed only once within the email client, even if it appears on multiple shared calendars on the server-side. He said that for ActiveSync clients, it is up to the client to decide on how to display calendar events with the same UID, as either a single event, or multiple events. 

Non-Responsive Mailboxd Process and AWS Storage Buckets 
Mark S. shared that he recently experienced an issue with one of his Zimbra mailbox servers where none of the users could access their mailboxes, but the mailboxd processes and its dependencies were running with a load of 120%. After a restart of the mailboxd and related services, users still could not access their mailboxes. With Zimbra Support’s assistance, the issue was pinpointed to a problem with mailboxd accessing the AWS storage buckets containing his Zimbra server’s disk volumes. He said that when using AWS storage buckets as Zimbra volumes, he used to be able to create a primary/secondary volume without also needing to create a logical representation in Zextras of the external AWS S3 storage bucket. But, he discovered that now this is required. Cine said that about one year ago, the Zimbra Administration UI changed to add support for some updates to the supported volume types, but the Zextras back-end CLI did not. He said that it should now no longer be possible to create a Zimbra volume without a corresponding AWS S3 bucket. When using AWS buckets for Zimbra volumes, Cine recommended running these CLI commands: 

    * “zxsuite hsm getAllVolumes” to get the bucketConfigurationId value, then run: 
    * “zxsuite hsm listBuckets” to see the actual bucketConfigurationId for your actual buckets. 
    * If your primary or secondary storage volume references a non-existent bucket ID, you may need to run “zxsuite hsm doUpdateVolume …” to fix. 

Using Smart Hosts In Zimbra To Manage Outbound Email Routing 
Noah P. re-visited a topic from the November 10th Zeta Alliance call ( [ https://forums.zimbra.org/viewtopic.php?f=9&t=68942#p299710 | https://forums.zimbra.org/viewtopic.php?f=9&t=68942#p299710 ] ) related to controlling SMTP mail flow in Zimbra per domain. He said he had been continuing to experiment with this capability by working with using the Zimbra Smart Hosts feature to attempt to direct mail per domain through specific Zimbra MTAs. Mark S. suggested that Noah should use the “zimbraSmtpHostname” setting per domain for this purpose, but Noah said this setting only works for users who access their mailboxes with the SOAP clients, such as the Zimbra Connector for Outlook and ActiveSync. Noah has observed that the Zimbra Web Client, SMTP (IMAP/POP) clients, mailbox forwarders, and distribution lists still continue to use the Zimbra global MTA setting, ignoring the per domain “zimbraSmtpHostname” setting. Cine suggested using Postfix’s “sender_dependent_relayhost_maps” attribute in addition to the “zimbraSmtpHostname” setting to help ensure consistency for each user’s email client use case. John H. suggested that Noah should also create a Zimbra request for enhancement to make this capability part of Zimbra’s official features. 

“Host or domain name not found” Errors During Zimbra Server Migration 
Matthew F. said that he is working on a customer migration from an old to a new Zimbra server version. He said that after a mailbox is moved from the old to the new server, the LMTP server address for the mailbox, that Zimbra uses for mail delivery, is updated to the new server’s fully qualified domain name (FQDN) as expected, but email deliveries sent from mailboxes on the old server to the mailbox on the new server result in “status=bounced (Host or domain name not found. Name service error for name=xxxx type=A: Host not found)” error messages in mailbox.log. He found that after moving a mailbox to the new Zimbra server, and changing the LMTP FQDN for a mailbox to an IP address, this then allows for email to be delivered normally. Noah P. wondered if Zimbra may be checking the server’s local /etc/hosts file before using the DNS resolver configured for the server, and the /etc/hosts file contains an incorrect entry for the FQDN of the new server. Mark S. said that he worked with a customer that had a multi-homed Zimbra server, with one network interface assigned to a public IP address, and another assigned to a VPN. He found it very tricky to get mail routed correctly with this setup and suggested using Postfix’s “lmtp=native” setting. He said that without this setting, Postfix avoided using the /etc/hosts file for look-ups and always used the DNS resolver configured for the server. Cine suggested that Matthew take a look at using dnsmasq as it makes these types of scenarios much easier. Mark S. suggested taking a look at his dnsmasq how-to ( [ https://www.missioncriticalemail.com/2018/04/12/zimbra-dnsmasq-configuration-guide/ | https://www.missioncriticalemail.com/2018/04/12/zimbra-dnsmasq-configuration-guide/ ] ) and said that dnsmasq is beneficial since it only answers DNS queries for records it is specifically configured to answer, and passes all other queries through to the server’s regular DNS resolver. Noah P. also suggested the Zimbra command: “zmlocalconfig -e postfix_lmtp_host_lookup=native” which Matthew said he currently has enabled. Cine added that using the /etc/nsswitch.conf file to set the order in which DNS resolvers are used may help, such as this configuration value: “hosts: files dns”. Mark S. said that this page ( [ https://wiki.zimbra.com/wiki/Postconf_keys | https://wiki.zimbra.com/wiki/Postconf_keys ] ) maps Postfix configuration settings to Zimbra-equivalent settings may be of help too. Noah P. said that Matthew might be looking for this Zimbra setting too: “zimbraMtaLmtpHostLookup”, which can be described from the CLI using: “zmprov desc -a zimbraMtaLmtpHostLookup”. Matthew F. said he currently has this setting configured: “zimbraMtaLmtpHostLookup: dns”. 

Randy Leiker ( randy at skywaynetworks.com ) 
Skyway Networks, LLC 

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