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If you have a Salesforce.com username (email address) over 32 characters long than the Salesforce.com Zimlet doesn't work.
Unfortunately, where I work we have an incredibly long domain name. This means some of the users are exceeding the limit imposed by the Salesforce.com Zimlet which only allows 32 characters for the username.
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Salesforce.com Zimlet Limits Username to 32 Chars 
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