Calddavmail.exchange.ExchangeSession (Ignore etag check, meeting response) && davmail.exchange.ews.EWSMethod (ErrorCalendarIsOrganizerForAccept)

[ifrh]

In GitHub issue #493 (comment) @mguessan wrote:

your issue is not the same as original ticket issue, however I found a potential root cause: a very old Exchange 2007 workaround on organizer participation state on event creation.

This is probably no longer relevant => dropped workaround.

I can't test it because it's Exchange 2007 only => can you please confirm which version of Exchange you have (should appear on initial session creation).

I rebuild DavMail from source using commit 5ae31d8 from 19.06.2026.
davmail-6.8.0-trunk-windows-standalone_gh493_commit5ae31d8_2026-06-19/davmail.jar

Dump of event content, Exchange version and other communication steps are inside this part of Davmail logfile: log_extract.txt

2026-06-20 10:33:41,720 ERROR [CaldavConnection-59505] davmail  - ErrorCalendarIsOrganizerForAccept Sie können diese Besprechung nicht annehmen, weil Sie der Besprechungsorganisator sind. 
 request: <soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/" xmlns:t="http://schemas.microsoft.com/exchange/services/2006/types" xmlns:m="http://schemas.microsoft.com/exchange/services/2006/messages"><soap:Header><t:RequestServerVersion Version="Exchange2013_SP1"/></soap:Header><soap:Body><m:CreateItem SendMeetingInvitations="SendToAllAndSaveCopy" MessageDisposition="SendAndSaveCopy"><m:SavedItemFolderId><t:DistinguishedFolderId Id="sentitems"/></m:SavedItemFolderId><m:Items><t:AcceptItem><t:ReferenceItemId Id="AAMkADUwMDMzNzE4LTE4MTAtNGI5MS04ODdhLWRmZmQ3OWMwYTkyOABGAAAAAAARvo6fWCehSbClzua/49TUBwBk0HrAF/J5QpCX8Bxj/ghqAAAAAAENAADKP+QC8H3LQbx/UHaYRmdvAAR4nTswAAA=" ChangeKey="DwAAABYAAADKP+QC8H3LQbx/UHaYRmdvAAR4itXQ"/></t:AcceptItem></m:Items></m:CreateItem></soap:Body></soap:Envelope>
davmail.exchange.ews.EWSException: ErrorCalendarIsOrganizerForAccept Sie können diese Besprechung nicht annehmen, weil Sie der Besprechungsorganisator sind. 
 request: <soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/" xmlns:t="http://schemas.microsoft.com/exchange/services/2006/types" xmlns:m="http://schemas.microsoft.com/exchange/services/2006/messages"><soap:Header><t:RequestServerVersion Version="Exchange2013_SP1"/></soap:Header><soap:Body><m:CreateItem SendMeetingInvitations="SendToAllAndSaveCopy" MessageDisposition="SendAndSaveCopy"><m:SavedItemFolderId><t:DistinguishedFolderId Id="sentitems"/></m:SavedItemFolderId><m:Items><t:AcceptItem><t:ReferenceItemId Id="AAMkADUwMDMzNzE4LTE4MTAtNGI5MS04ODdhLWRmZmQ3OWMwYTkyOABGAAAAAAARvo6fWCehSbClzua/49TUBwBk0HrAF/J5QpCX8Bxj/ghqAAAAAAENAADKP+QC8H3LQbx/UHaYRmdvAAR4nTswAAA=" ChangeKey="DwAAABYAAADKP+QC8H3LQbx/UHaYRmdvAAR4itXQ"/></t:AcceptItem></m:Items></m:CreateItem></soap:Body></soap:Envelope>
	at davmail.exchange.ews.EWSMethod.checkSuccess(Unknown Source)
	at davmail.exchange.ews.EwsExchangeSession.internalExecuteMethod(Unknown Source)
	at davmail.exchange.ews.EwsExchangeSession.executeMethod(Unknown Source)
	at davmail.exchange.ews.EwsExchangeSession$Event.createOrUpdate(Unknown Source)
	at davmail.exchange.ews.EwsExchangeSession.internalCreateOrUpdateEvent(Unknown Source)
	at davmail.exchange.ExchangeSession.createOrUpdateItem(Unknown Source)
	at davmail.caldav.CaldavConnection.handleFolderOrItem(Unknown Source)
	at davmail.caldav.CaldavConnection.handleRequest(Unknown Source)
	at davmail.caldav.CaldavConnection.run(Unknown Source)

From Thunderbird error log:

11:03:27.903 Calendar: [calCachedCalendar] Performing playback operation modify on 1 items to Kalender (DAVmail) CalCachedCalendar.sys.mjs:550:11
11:03:27.919 Calendar: CalDAV: send: BEGIN:VCALENDAR :  <....>  CalDavCalendar.sys.mjs:2443:11
11:03:27.948 Calendar: CalDAV: send (PUT http://localhost:1080/users/<EMAIL-ADDRESS>/calendar/A<MULTIPLE-SIGNS>%3D.EML): BEGIN:VCALENDAR <...> CalDavRequest.sys.mjs:109:11
11:03:29.596 Calendar: CalDAV: recv: ErrorCalendarIsOrganizerForAccept Sie können diese Besprechung nicht annehmen, weil Sie der Besprechungsorganisator sind. 
 request: <soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/" xmlns:t="http://schemas.microsoft.com/exchange/services/2006/types" xmlns:m="http://schemas.microsoft.com/exchange/services/2006/messages"><soap:Header><t:RequestServerVersion Version="Exchange2013_SP1"/></soap:Header><soap:Body><m:CreateItem SendMeetingInvitations="SendToAllAndSaveCopy" MessageDisposition="SendAndSaveCopy"><m:SavedItemFolderId><t:DistinguishedFolderId Id="sentitems"/></m:SavedItemFolderId><m:Items><t:AcceptItem><t:ReferenceItemId Id="<DELETED-ID>" ChangeKey="<DELETED-KEY>"/></t:AcceptItem></m:Items></m:CreateItem></soap:Body></soap:Envelope> CalDavRequest.sys.mjs:122:13
11:03:29.597 Calendar: [calCachedCalendar] Could not perform playback operation modify for item Gremien-Information "Einführung eines Chatbots": Server Replied with 503 CalCachedCalendar.sys.mjs:503:15

11:03:29.597 Calendar: [calCachedCalendar] Unable to perform playback action modify to the server, will try again next time (040000008200E00074C5B7101A82E008000000001012E79A09E2DC010000000000000000100000009F71BBDC46AD564690CE136421674DA7,Server Replied with 503) CalCachedCalendar.sys.mjs:522:15

11:03:29.603 Calendar: [calCachedCalendar] Doing changelog based sync for calendar http://localhost:1080/users/<E-MAIL-ADDRESS>/calendar/ CalCachedCalendar.sys.mjs:292:13
11:03:29.604 Calendar: CalDAV: send (PROPFIND http://localhost:1080/users/<E-MAIL-ADDRESS>/calendar/): <?xml version="1.0" encoding="UTF-8"?><D:propfind xmlns:D='DAV:' xmlns:C='urn:ietf:params:xml:ns:caldav' xmlns:CS='http://calendarserver.org/ns/'><D:prop><D:resourcetype/><D:owner/><D:current-user-principal/><D:current-user-privilege-set/><D:supported-report-set/><C:supported-calendar-component-set/><CS:getctag/></D:prop></D:propfind> CalDavRequest.sys.mjs:109:11
11:03:29.909 Calendar: CalDAV: recv: <?xml version="1.0" encoding="UTF-8"?><D:multistatus xmlns:D="DAV:" xmlns:C="urn:ietf:params:xml:ns:caldav" xmlns:E="urn:ietf:params:xml:ns:carddav"><D:response><D:href>/users/<E-MAIL-ADDRESS>/calendar/</D:href><D:propstat><D:prop><D:resourcetype><D:collection/><C:calendar/></D:resourcetype><D:owner><D:href>/principals/users/<E-MAIL-ADDRESS></D:href></D:owner><CS:getctag xmlns:CS="http://calendarserver.org/ns/">MjAyNi0wNi0yMFQwODoxODo1MloyMDI2LTA1LTI5VDE2OjM3OjM4Wg==</CS:getctag><C:supported-calendar-component-set><C:comp name="VEVENT"/><C:comp name="VTODO"/></C:supported-calendar-component-set><D:current-user-privilege-set><D:privilege><D:read/><D:write/></D:privilege></D:current-user-privilege-set></D:prop><D:status>HTTP/1.1 200 OK</D:status></D:propstat></D:response></D:multistatus> CalDavRequest.sys.mjs:122:13
11:03:29.909 Calendar: CalDAV: Status 207 on initial PROPFIND for calendar Kalender (DAVmail) CalDavCalendar.sys.mjs:1524:13
11:03:29.909 Calendar: CalDAV: Authentication scheme for Kalender (DAVmail) is Basic CalDavCalendar.sys.mjs:1559:13
11:03:29.910 Calendar: CalDAV: initial ctag MjAyNi0wNi0yMFQwODoxODo1MloyMDI2LTA1LTI5VDE2OjM3OjM4Wg== for calendar Kalender (DAVmail) CalDavCalendar.sys.mjs:1601:17
11:03:29.911 Calendar: Adding supported items: VEVENT,VTODO for calendar: Kalender (DAVmail) CalDavCalendar.sys.mjs:1611:15
11:03:29.911 Calendar: CalDAV: Found principal url from DAV:owner /principals/users/<E-MAIL-ADDRESS> CalDavCalendar.sys.mjs:1629:15

For unstoppable Thunderbird action playback operation modify I create a bug report https://bugzilla.mozilla.org/show_bug.cgi?id=2048378.

[ifrh]

If needed here is the content of davmail64.ini having davmail.caldavImpersonate as advised in #419 (comment) :

ini.override=true
vm.location=./jre/bin/server/jvm.dll
vm.sysfirst=false

main.class=davmail.DavGateway
classpath.1=davmail.jar
classpath.2=lib/activation-1.1.1.jar
classpath.3=lib/commons-codec-1.15.jar
classpath.4=lib/commons-collections-3.1.jar
classpath.5=lib/commons-logging-1.0.4.jar
classpath.6=lib/htmlcleaner-2.29.jar
classpath.7=lib/httpclient-4.5.14.jar
classpath.8=lib/httpcore-4.4.16.jar
classpath.9=lib/jackrabbit-webdav-2.20.15.jar
classpath.10=lib/javax.mail-1.6.2.jar
classpath.11=lib/jcharset-2.0.jar
classpath.12=lib/jcifs-1.3.19.jar
classpath.13=lib/jdom-1.0.jar
classpath.14=lib/jettison-1.5.4.jar
classpath.15=lib/reload4j-1.2.26.jar
classpath.16=lib/slf4j-api-2.0.16.jar
classpath.17=lib/slf4j-reload4j-2.0.16.jar
classpath.18=lib/stax-api-1.0.1.jar
classpath.19=lib/stax2-api-3.1.1.jar
classpath.20=lib/winrun4j-0.4.5.jar
classpath.21=lib/woodstox-core-6.4.0.jar
classpath.22=lib/swt-4.37-win32-x86_64.jar

vm.version.min=1.8
vmarg.1=-Dsun.net.inetaddr.ttl=60
vmarg.2=-Xmx512M
vmarg.3=--add-exports
vmarg.4=java.base/sun.net.www.protocol.https=ALL-UNNAMED

davmail.caldavImpersonate

[ErrorMessages]
java.not.found=A suitable version of Java could not be found on your system, please install Java (64-bit) from http://java.com/en/download/manual.jsp
java.failed=Java failed to startup successfully, please install Java (64-bit) from http://java.com/en/download/manual.jsp

[esabol]

@mguessan wrote:

can you please confirm which version of Exchange you have (should appear on initial session creation).

I think you have yet to do that, @ifrh !

[ifrh]

Does something change if I use davmail.caldavImpersonate=true and not only davmail.caldavImpersonate as told in #419 (comment) ?

=> It does not change the Thunderbird behavior.

From DavMails log, above attached as file in #495 (comment),

2026-06-20 10:33:40,580 DEBUG [CaldavConnection-59505] davmail.exchange.ExchangeSession  - Current user email is PERSONAL_EMAIL-ADDRESS@DOMAIN.TLD, alias is PERSONAL-EMAIL-ADDRESS on Exchange2013_SP1

I think it is Exchange2013_SP1.

If I turn on DEBUG WIRE also (not in that log file), than I can see multiple Version information ...

org.apache.http.wire  - http-outgoing-1 << "Server: Microsoft-IIS/10.0[\r][\n]"
org.apache.http.wire  - http-outgoing-1 << "X-OWA-Version: 15.2.2562.43[\r][\n]"
org.apache.http.headers  - http-outgoing-1 << X-FEServer: EX4
org.apache.http.wire  - http-outgoing-1 << "X-DiagInfo: EX4[\r][\n]"
org.apache.http.wire  - http-outgoing-1 << "X-BEServer: EX4[\r][\n]"
org.apache.http.wire  - http-outgoing-1 << "X-AspNet-Version: 4.0.30319[\r][\n]"
[...]
org.apache.http.wire  - http-outgoing-1 >> "<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/" xmlns:t="http://schemas.microsoft.com/exchange/services/2006/types" xmlns:m="http://schemas.microsoft.com/exchange/services/2006/messages"><soap:Header><t:RequestServerVersion Version="Exchange2013_SP1"/></soap:Header><soap:Body><m:GetFolder><m:FolderShape><t:BaseShape>IdOnly</t:BaseShape><t:AdditionalProperties><t:ExtendedFieldURI PropertyTag="0x360a" PropertyType="Boolean"/><t:ExtendedFieldURI PropertyTag="0x6751" PropertyType="Integer"/><t:ExtendedFieldURI PropertyTag="0x3008" PropertyType="SystemTime"/><t:ExtendedFieldURI PropertyTag="0x670a" PropertyType="SystemTime"/><t:FieldURI FieldURI="folder:DisplayName"/><t:ExtendedFieldURI PropertyTag="0x3602" PropertyType="Integer"/><t:ExtendedFieldURI PropertyTag="0x3603" PropertyType="Integer"/><t:ExtendedFieldURI PropertyTag="0x10f3" PropertyType="String"/><t:ExtendedFieldURI PropertyTag="0x3613" PropertyType="String"/><t:ExtendedFieldURI PropertyTag="0x6752" PropertyType="Integer"/></t:AdditionalProperties></m:FolderShape><m:FolderIds><t:DistinguishedFolderId Id="contacts"/></m:FolderIds></m:GetFolder></soap:Body></soap:Envelope>"

[mguessan]

No worries @esabol, found in the log:
Current user email is PERSONAL_EMAIL-ADDRESS@DOMAIN.TLD, alias is PERSONAL-EMAIL-ADDRESS on Exchange2013_SP1

=> so not Exchange 2007

We have:

Item found, detected a meeting response => send accept request:

2026-06-20 10:33:41,621 DEBUG [CaldavConnection-59505] davmail.exchange.ExchangeSession - Existing item found with etag: 2026-06-10T12:53:51Z client etag: 2026-06-10T12:53:51Z id: AAMkADUwMDMzNzE4LTE4MTAtNGI5MS04ODdhLWRmZmQ3OWMwYTkyOABGAAAAAAARvo6fWCehSbClzua/49TUBwBk0HrAF/J5QpCX8Bxj/ghqAAAAAAENAADKP+QC8H3LQbx/UHaYRmdvAAR4nTswAAA=
2026-06-20 10:33:41,621 DEBUG [CaldavConnection-59505] davmail.exchange.ExchangeSession - Ignore etag check, meeting response
2026-06-20 10:33:41,717 DEBUG [CaldavConnection-59505] davmail.exchange.ews.EWSMethod - ErrorCalendarIsOrganizerForAccept

PERSONAL-EMAIL-ADDRESS is your email address on calendar, correct?
organizer.name@DOMAIN.TLD is event organizer, not same email?

ORGANIZER;CN="ORGANIZER, NAME";SCHEDULE-AGENT=CLIENT:mailto:organizer.name@DOMAIN.TLD
ATTENDEE;RSVP=TRUE;CN="SOME, NAME";PARTSTAT=NEEDS-ACTION;ROLE=REQ-PARTICIPANT:mailto:SOME.NAME@DOMAIN.TLD
ATTENDEE;RSVP=TRUE;CN="SHARED ROLE NAME";PARTSTAT=NEEDS-ACTION;ROLE=REQ-PARTICIPANT:mailto:E-MAIL-ADDRESS-SHARED-CALENDAR@DOMAIN.TLD
ATTENDEE;RSVP=TRUE;CN="USER, NAME";PARTSTAT=ACCEPTED;ROLE=REQ-PARTICIPANT:mailto:PERSONAL-EMAIL-ADDRESS@DOMAIN.TLD

=> can you please check in OWA event properties from an Exchange point of view?

[ifrh]

PERSONAL-EMAIL-ADDRESS is your email address on calendar, correct?

Yes, for issue reporting the real one is pseudonymized. But in unedited log file, there is written my personal mail address.

E-MAIL-ADDRESS-SHARED-CALENDAR@DOMAIN.TLD is also pseudonymized.

Calendars of both addresses are subscriebed in Thunderbird using the same running davmail instance, since both calendars are delivered from same Exchange server.

organizer.name@DOMAIN.TLD is event organizer, not same email?

Yes, the E-Mail address of organizer is different from both others.

=> can you please check in OWA event properties from an Exchange point of view?

If you are asking about log informations created on the Exchange server, than sadly I have to ask the admin...

Are OWA event properties not inside the given logfile - or which logging setting I should change?

[edit: some line breaks were needed in my response. Fixed my answer.]

[mguessan]

Also @ifrh the ini file is just a launcher, not your settings file .davmail.properties that probably lives in your user folder.

Anyway this is not the issue there: DavMail acts according to what we see in the caldav content: not organizer, PARTSTAT set to accepted for user => this is a meeting response.

To be more clear on my request: connect to outlook web, open your personal calendar then the exact event: in scheduling who is the organizer ? Can you edit event or just display and accept/reject?

[ifrh]

click on shared calendar entry (as expected):

click on personal calendar entry (it seems to me, that here I can edit the event. "Bearbeiten" is German for editing.):

[ifrh]

Oh ... perhaps ... that could be the reason ...
I am using two different systems, calling them A and B.

On A davmail is running and connecting to both calendars.
On B davmail is not running but only the personal calendar is connected using tbsync.

As I told I had accepted the invitation delivered via E-Mail (IMAP) on A at a time where I forgot to start davmail.
On this system Thunderbird put an operation to its cache, and from now on Thunderbird try to do the replay of modification.

For whatever reason I had to switch to B. After doing some work on B, I wrote some mail from shared address - and saw the invitation for that shared address (for same event).
I transfer this event from shared address imap inbox to my personal calendar, perhaps in this way, using click on mails context menue

Or just do an accept the by others forwarded mail from my personal IMAP inbox in Thunderbird relaying on tbsync connection to Exchange...

Sadly I do not remember on which way the calendar event for my personal mail had been "activated" ...