Hi Olivier,
Sorry for any inconvenience caused to you.
Can you please tell us if this was working fine with an earlier version of Aspose.Words? If it is so, we need to look if this problem occurred due to Aspose.Email or due to Aspose.Words.
You may check it by using the latest version of Aspose.Email of .NET 2.5.0 with the earlier as well as latest version of Aspose.Words. This will confirm if the problem lies at the Aspose.Email or Aspose.Words end and can be investigated properly then.
If the issue is due to some latest version of Aspose.Words, I would request you to contact the Aspose.Words team to look into this issue then.
If you find the issue at Aspose.Email end, I would request you to please create a new thread for this issue, and provide us a runnable sample console application that we can use to reproduce this issue at our end. We will investigate it and try to fix it.