Norton Internet Security 2010 - Email Error

When I was looking at my e-mail using Outlook Express an e-mail error window popped up which said:

 

450 4.2.1 Authentications from (e-mail address) are declined at this time.

 

The e-mail was from a valid e-mail address but the subject was not.

 

Any answers to this problem would be much appreciated.

 

Thank you,

 

 

 

When I was looking at my e-mail using Outlook Express an e-mail error window popped up which said:

 

450 4.2.1 Authentications from (e-mail address) are declined at this time.

 

The e-mail was from a valid e-mail address but the subject was not.

 

Any answers to this problem would be much appreciated.

 

Thank you,