Error Code: 0x800420C8

Similar Symptom:

Message Could Not Be Opened From Outbox Folder, Account: MailAccount’,Server:’ ’, Protocol:SMTP,PORT:25,Secure(SSL):NO, Error Number:0x800420CB
(various SRX cases have the error code mislabelled at 0x800420C8)
 

Possible Cause:
 
This behavior can occur if you have two identical accounts with different names or the Outbox.dbx file is corrupted. 

 
Resolution:
 
Delete and reset the email account in outlook and make sure there’s only one identical email.
Desktop version