Mail Portlet - When attempt to send a message you'll get: "Unable to send message." error message

• Type: Bug
• Status: Closed
• Resolution: Fixed
• Affects Version/s: 6.1.1 CE GA2, 6.1.20 EE GA2
• Fix Version/s: 6.1.2 CE GA3, 6.1.30 EE GA3, 6.2.0 CE M6
• Component/s: Mail, ~ [Archived] Collaboration
• Labels:
  • QA-R
  • QA-TP
  • ee-ts
  • ee-ts-labs
• Branch Version/s:
  6.1.x
• Backported to Branch:
  Committed
• Story Points: 8
• Git Pull Request: https://github.com/hhuijser/liferay-plugins/pull/113

Steps to reproduce:

1) Deploy the Mail EE portlet version 1.0.0 on a vanilla Liferay 6.1.20 (No portal-ext.properties)
2) Add the Mail portlet to the Welcome page
3) Set up a test gmail account (IMAP enabled) successfully!
4) Click on the "Compose Email" function
a) Fill out the following inputs: To,Subject,Body
b) Click on save button
c) Choose an attachment
d) Save again
5) Attempt to send an email message

Observed behavior: Now you get the red warning message: "Unable to send message." and also got some exceptions in the log file. Attached: "liferay.2013-04-29.log"

Another try, I've got these exceptions: "liferay.2013-04-30.log" with another account (custom one in my case)
These accounts and the above functions works correctly if I add these accounts beside a specified one.