Personally, I find the hyperlink fields to be a great nuisance due to issue such as this...
+ You should double check the format of your hyperlink, could be that there is something wrong in the syntax - I don't expect this to be the root cause; however, it's the easiest first step to check.
+ You don't say this, however, I get the impression that you have one version of Access and a different version of Outlook and that could be the issue. Different versions do not always play well with each other.
+ For very simple emails, What I usually do is setup a control that feeds the current record email to:
DoCmd.SendObject acSendNoObject, , , [EMailAddress]
This is a little more bullet-proof than using a hyperlink file.
If you will search here on Bytes.com there are several threads dealing with sending emails via outlook and other methods. Indeed our application automation article provides a basic implementation of such code for outlook:
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