I setup database mail on a SQL Server 2005 instance and kept getting this log message whenever an email was tried:
Message 1) Exception Information Exception Type: System.NullReferenceException Message: Object reference not set to an instance of an object. Data: System.Collections.ListDictionaryInternal TargetSite: Microsoft.SqlServer.Management.SqlIMail.Server.Objects.AccountGetAccount(Int32) HelpLink: NULL Source: DatabaseMailEngine
After checking to make sure my setup was correct, I tried adding the service account user to the sysadmin group, which resolved the problem.
But I'd like to know if that's necessary, or if the particular permissions issue was simply blanketed by the sysadmin role. Is there some more granular permission that I should be using?