GlobalSCAPE Knowledge Base

Email gets stuck in the Outbox after Microsoft update

Karla Marsh
Mail Express - DEPRECATED


  • Mail Express version 3.1


Email gets stuck in the Outbox after one of the following Microsoft updates is installed:

  • Update for Microsoft Visual Studio 2010 Tools for Office Runtime Redistributable (KB2525428)
  • Service Pack 1 for Microsoft Office 2010 (KB2510690)


The workaround below is provided for non-administrator users on their desktops. For administrators, scroll down for a resolution to this problem.

(Outlook 2010 screen shots are shown below; however, the basic steps are the same in Outlook 2007.)

Disable the Mail Express Outlook Add-In via the Outlook Trust Center, and then remove the deferred delivery date for messages stuck in the outbox.

  1. Open the Outlook Add-Ins interface:
    • In Outlook 2010, click File -> Options -> Add-Ins.
    • In Outlook 2007, click Tools > Trust Center, then click Add-Ins.

  2. In the Manage drop-down box, click COM Add-ins, then click Go. The COM Add-Ins dialog box appears.
  3. Clear the Mail Express Outlook Addin check box, then click OK.
  4. Open the message that is stuck in the Outbox.
  5. Click Options, then in the More Options area, click Delay Delivery. The message Properties dialog box appears.
  6. Clear the Do not deliver before check box, then click Close.
  7. Remove any attachments that have the .MailExpress extension and then reattach them using Outlook's Attach File button.
  8. Send the message.


The update for Microsoft Visual Studio 2010 Tools for Office Runtime Redistributable (KB2525428) was recently released by Microsoft and deployed on user workstations here at GlobalSCAPE. For Outlook 2010 and Outlook 2007 Mail Express users, this update may change a registry setting which denotes the path to the Mail Express Add-in’s Deployment Manifest.

To resolve this issue, do one of the following:

  • Run the Mail Express installer in repair mode. Repairing the Mail Express installation should correct the registry setting.
  • Uninstall Mail Express and reinstall. Reinstalling Mail Express should correct the registry setting.
  • Edit one of the following registry settings, depending on your version of Outlook:
  • NOTE: Editing the registry is for advanced users. If you need instructions for how to edit the registry, please refer to the GlobalSCAPE Knowledgebase article at

Outlook 2010 Add-in Registry location:


Outlook 2007 Add-in Registry location:


Change the value from (for example, for the Outlook 2007 Add-In with default installation paths):

C:\Documents and Settings\<user>\Application Data\GlobalSCAPE\Mail Express Outlook Addin\MailExpressOutlook2007Addin.vsto


C:\Documents and Settings\<user>\Application Data\GlobalSCAPE\Mail Express Outlook Addin\MailExpressOutlook2007Addin.vsto|vstolocal

Edit the path to match your Mail Express installation, as in the screen shot below:


From this MSDN article Microsoft states the following:

If you use Windows Installer to deploy the solution, append the string |vstolocal (that is, the pipe character | followed by vstolocal) to the end of this path. This ensures that your solution is loaded from the installation folder, rather than the ClickOnce cache.

The Mail Express Add-in expects for its assemblies to be loaded from the add-in’s installation location so that it knows where to access files it needs, such as the log configuration file “log4net_log_config.xml,” the redemption DLL “Redemption.dll”, and also to save the user's settings in this location. If the add-in is loaded from the "click-once cache," these auxiliary files will not be found, which leads to errors when using the add-in. At this time we have been able to reproduce this issue in Outlook 2010. In Outlook 2007, we know of one user who has experienced this problem, but we have been unable to reproduce it by installing the Microsoft Visual Studio 2010 Tools for Office Runtime Redistributable.

The following symptoms are known to occur in Outlook 2010 and Outlook 2007.

Sending emails regardless of whether they have attachments will cause them to remain in the Outlook outbox. This occurs because the add-in is unable to locate the third-party library Redemption.dll which it needs to properly analyze the email.

Refer also to KB10618.

Last Modified: Last Year
Last Modified By: kmarsh
Type: FIX
Rated 1 star based on 16 votes.
Article has been viewed 72K times.
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