Our notifications have a limit of size 2MB.  Even then we got a few of the below errors recently:
8/29/2011 5:42:46 AM    Info        Job completed: DWAYSegWay_LUM_05Min_YWAYCleanDirtyObjects
8/29/2011 5:42:46 AM    Debug   Running Email Notification: 'Default E-mail of Job Status (TF Language Jobs Only w/ Function name in Description) - SegWay (with attachment)'
8/29/2011 5:42:46 AM    Info        Job completed: DWAYSegWay_AEP_00.5Min_YWAYFeedSolr
8/29/2011 5:42:46 AM    Info        Job completed: DWAYSegWay_SCEQA_05Min_YWAYCleanDirtyObjects
8/29/2011 5:42:46 AM    Err          Email report error, error: OpenSmtp.Mail.SmtpException: ERROR - Expecting: 250. Recieved: 552 4.3.1 Message size exceeds fixed maximum message size
   at OpenSmtp.Mail.Smtp.CheckForError(String s, String successCode)
   at OpenSmtp.Mail.Smtp.SendMail(MailMessage msg)
   at OBOKIIHBDBPMCFALPGECCIFHCDJPEDKODDGK.IEFFKAIGNHHBGJNIJAKKLFKNFMFIFMJPNFHE.AFHONCCFKPJAADEPFNAPMCIJINEGFIFKDIAJ(VariableReplacerClass )
Any ideas?
Thanks,
DevonWay