QB Issue Resolution:

Yes, this is part of the discontinuation of support for 2011, although it is due to begin as of 5/31/14. You can save your documents as PDFs and email from your email client.

Resolution for Issue 'trying to change email' available: Yes (Solved).
Source: Intuit Community forum.

trying to change email: this issue or error code is a known issue in Quickbooks Online (QBO) and/or Quickbooks. Support for this issue is available either by self-service or paid support options. Experts are available to resolve your Quickbooks issue to ensure minimal downtime and continue running your business. First try to resolve the issue yourself by looking for a resolution described below. If it is a complex issue or you are unable to solve the issue, you may contact us by clicking here or by using other support options.

Support for Invoice
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Error Recovery for Invoice [Canada]
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Additional Support Options: