Users cannot process or open meeting invites sent from Lotus Notes. They receive 2 .ics attachments and one is named "not supported calendar message.ics"
Outlook users can't accept meeting invite from Notes users
Per Microsoft's article http://support.microsoft.com/kb/2643084:
"The "not supported calendar message.ics" attachment is created when the original .ics file cannot be converted to an Outlook or Microsoft Exchange meeting type. The conversion fails if one or more of the following conditions are true: 1.The meeting contains a recurrence pattern that is available to a third-party email client, such as Lotus Notes. However, this recurrence pattern is not supported by Outlook:
1. Monthly by Date: Every month on the nth day and the nth day. Outlook only supports one nth day of the month.
2. Monthly by Day: Every month on the nth day of the week and the nth day of the week. Outlook only supports one nth day of the week in any month.
3. Custom recurrence: Outlook does not support custom recurrence patterns that are available in some third-party email clients, such as Lotus Notes.
Also, if the meeting contains a recurrence pattern that is defined by the RDATE property. However, the meeting does not include a corresponding RRULE property. In this case, Outlook does not open the item, even if the RDATE property specifies a supported recurrence pattern"
8.5.1 and above
Resolving the problem
Please note that the use of the RDATE property is fully supported through the RFC 5545 (2445) standards. Since custom repeating meetings cannot be specified using a defined recurrence pattern which is the purpose of the RRULE, Notes/Domino uses the RDATE value to list the specific dates requested for a custom repeating meeting.
To prevent such problems from Notes, compatibility mode may be enabled. Compatibility mode can be configured to be engaged only when sending to certain domains or when sending to an internet address via a mail policy as to not negatively affect custom repeating meeting routed within the Domino domain. However, when it is engaged when routing externally, it will prevent the creation of custom repeat meetings as they are not supported by Outlook/Exchange and possibly other third-party applications. Please know that enabling this feature will also prevent the ability to reschedule or cancel multiple instances of a repeating meeting.
To configure compatibility mode, the following parameters may be set in the client and mail server notes.ini, but it is recommended to enable compatibility mode using a mail policy which is discussed in more detail in Technote # 1389862
Using ini parameters to set compatibility mode:
1. If your organization does not require Outlook/Exchange interoperability, set $CSCompatibilityMode=0 on all clients and servers.
2. If you require Outlook/Exchange interoperability but do not want to require end users to select the "Some invitees use other mail clients" option, do one of the following:
- Set DisallowRelatedIcalendarMime=2 on all clients and servers. This causes all non-repeating meetings to work, but complex actions on repeating meetings might not work.
- Set $CSCompatibilityMode=3 on all clients. This causes everything to work seamlessly but restricts repeating meeting options as described above. This setting displays the "Some invitees use other mail clients" option, but it will be automatically selected and dimmed.
3. If you require Outlook/Exchange interoperability and trust users to use the "Some invitees use other mail clients" option properly, do both of the following:
- Set $CSCompatibilityMode=2 in user's NOTES.INI files.
- Consider setting DisallowRelatedIcalendarMime=2 to ensure that meetings work even when the "Some invitees use other mail clients" option is not selected.
$CSCompatibilityMode - Specifies the behavior of the "Some invitees use other mail programs" option in repeating meetings. Use this notes.ini variable to show the option, change the default value, or lock the option on for all meetings.
- 0 - Option is hidden and off for all meetings created on that client.
- 1 - Option is hidden and defaults to on for all meetings created on that client. The chair cannot see the option nor make any changes to it.
- 2 - Option is displayed and defaults to off for all meetings created on that client. The meeting chair can use the option to set whether it is on or off for each meeting created. The chair can also update the selection later to turn the option on or off at that time.
- 3 - Option is displayed but is locked on for all meetings.
DisallowRelatedIcalendarMime - Manages MIME simplification in Domino 8.5.1. In 8.5.2 and above, it is recommended to use a mail policy instead of setting this parameter.
- 0 - Complex MIME conversion occurs as usual. No richness is lost, but workflow problems may result with Exchange 2003.
- 1 - Complex MIME conversion occurs as usual, unless a meeting has compatibility mode specified, in which case it is simplified for Exchange 2003 compatibility. Compatibility mode is represented by the text document property of $ICAL_COMPATIBILITY_MODE and a "1" value means it is on. If a third party creates the documents, it can set this property to control the generated MIME.
- 2 - MIME conversion is simplified. Richness, but no data, is lost for all users outside your Notes domain that require MIME conversion). No problems occur with Exchange 2003.
More information about DisallowRelatedIcalendarMime may be found here: