OL2000: Custom Forms and Programming Limitations

This article describes the known limitations that you may encounter when you create custom forms and programming solutions with Outlook. Issues that are covered in this article include limitations of the object model and other limitations that are related to the architectural design of Outlook.

Object Model Limitations

Unlike other Microsoft Office programs, Outlook does not provide a complete object model and the object model does not parallel the user interface. For additional information about specific limitations that are related to the Outlook object model, click the article number below to view the article in the Microsoft Knowledge Base:

General Storage Limitations

Storage limitations vary depending on whether data is stored in a Microsoft Exchange folder, a Personal Folders file (.pst), or an Offline Folder file (.ost). For additional information about limitations that are related to storage capacities, click the article numbers below to view the articles in the Microsoft Knowledge Base:

Custom Form Limitations

This section discusses known limitations related to items and custom forms.

Form Size Limitations

For additional information about limitations related to the number of fields or controls that you can have on an Outlook form, click the article numbers below to view the articles in the Microsoft Knowledge Base:

Field Size Limitations

For additional information about limitations related to the amount of data fields can contain, click the article number below to view the article in the Microsoft Knowledge Base:

Forms Available on the Actions Menu

Outlook forms that are published in a folder are displayed at the bottom of the Actions menu when you are in the folder. The Actions menu can display a maximum of 19 forms, even though you can publish more forms into the folder. When you publish forms to a Personal Folders File (.pst), only the first 19 published forms are available in the Actions menu. When publishing forms to a Microsoft Exchange Server mailbox, the 19 most recent published forms are available from the Actions menu. To access other forms that are published in the folder:

1. Select the folder in which the forms are published.
2. On the File menu, point to New, and then click Choose Form.
3. Change the Look in box so that it displays the name of the folder in which the forms are published.
4. Click the form that you want to open, and then click Open.

Number of Forms that You Can Publish in a Folder

There is no fixed limit to how many forms that you can publish to a folder, Personal Forms Library, or Organizational Forms Library. All published forms are stored as hidden items in a folder, so the limit is the same as the maximum number of messages that a folder can contain.

Editing Fields by Using the "All Fields" Page of a Form

If you view or change the contents of a Text field by using the All Fields page of a form, you are limited to 255 characters. However, if you access the field by using a control on an Outlook form, you can type more than 255 characters in the field. This is a limitation of the All Fields pages of a form and not the underlying storage capacity of the fields.

View Limitations

This section discusses known the limitations that are related to Outlook views.

Programmatically Creating or Modifying Views

Outlook does not support programmatically creating new view or modifying existing views. However, you can switch views. For additional information about this limitation, click the article number below to view the article in the Microsoft Knowledge Base:

Editing Fields by Using In-Cell Editing

If you view or change the contents of a Text field by using the In-cell editing feature, you are limited to 255 characters. However, if you access the field by using a control on an Outlook form, you can type more than 255 characters in the field. This is a limitation of the In-cell editing feature and not the underlying storage capacity of the fields.

For additional information about available resources and answers to commonly asked questions about Microsoft Outlook solutions, click the article number below to view the article in the Microsoft Knowledge Base: