[12] WHAT ARE THE LIMITS ON SENDING EMAIL FROM SDF?

     There are no limits on the number of messages you can send from SDF
     as long as it falls within the guildelines of the AUP.  That basically
     boils down to:  Send messages to your friends all you'd like, but 
     under no circumstances use the SDF mail server to send retaliatory or
     bulk/spam email.  If you do this, you will lose your account ASAP.

     MESSAGE SIZE:  Approximately 100MB, total size (header/body/attachments)

     This has changed (increased) over the years and probably will continue
     to increase as pipes fatten and disk prices drop.   Historically it 
     has been as low as 1MB during the early to mid 1990s.  It has increased
     over the past few years from 5mb, 8mb, 10mb, 16mb, 20mb and 30mb.

     MAX NUMBER OF RECIPIENTS:  20 addresses.

     This is the number of people in the To:, Cc: and Bcc: lines in your
     header that can receive a single piece of email from you.  If you are
     going to send email to so many people on a regular basis, we suggest
     the MLIST membership.

     Some server info:

     MAX NUMBER OF SERVERS:  128
   
     We currently allow up to 128 simultaneous server connections.  The 
     average number of active connections we have at the time of writing
     this is less than 50.  What this means is that, there would have to 
     be over 128 connections before the server begins denying connections.
     Those incoming emails would not be lost, but deferred for when the 
     email flood dies down.  For more information about how SMTP works, 
     see the previous entry for this FAQ.

     QUEUE RUN:  60 minutes

     When an outgoing email it deferred, it remains in the mailq queue for
     up to 5 days before being returned to sender.  Every message in the
     queue is retried every 60 minutes or roughly 120 times before it is
     returned to you.  For more information about how SMTP works, see the
     previous entry for this FAQ.