There is the  Sizelim  keyword in the list header, which controls the size of messages the list will accept.  This isn't specifically about attachments, but any attachments are included in the size of the message, so effectively you can get close to what you're asking.

For example, if you set  Sizelim=2M  then any message larger than two megabytes will be rejected.  This means no attachments 2Meg or larger can get through (if the attachment itself is 2Meg then when added to the message size it will be over the limit).  It also means if you have an extremely wordy subscriber who writes two megabytes of message body text, that won't get through either.  Or if someone embeds several images and they add up to more than 2Meg, that won't get through.  You have to pick a limit value that makes sense for your particular population.  Consult the documentation for details on how to specify the keyword and values.

>>> subramanyeswari <[log in to unmask]> 10/30/09 2:52 AM >>>
Is there a way to restrict the size of the attachment to a list?  

Regards