SMTP Relay

Overview

The CNS Open Systems Group maintains the campus-wide open-access Simple Mail Transfer Protocol (SMTP) server. This service is commonly referred to as the outgoing mail server. SMTP is used by Mail User Agents (MUA) to send and by Mail Transport Agents (MTA) to deliver messages to their destinations.

 

SMTP filtering for VPN networks

We no longer allow unauthenticated submission of mail on port 25 from VPN networks to smtp.ufl.edu due to increased activity from spammers. This change was announced on 5/30/2013 and went into affect 6/9/2013. See:VPN-L Archives.

You may be interested in: SPAM filtering and How to Report Incorrectly Classified Messages.

 

Networks and access

In order to maintain connectivity to smtp.ufl.edu (either because you list us in your MX record, or submit mail to us directly), please ensure your networks can access port 25 and/or 587 on the following addresses

    PRODUCTION

  • virtual-smtp-prod01.osg.ufl.edu (128.227.9.40)
  • smtp-prod01.osg.ufl.edu (128.227.74.217)
  • smtp-prod02.osg.ufl.edu (128.227.74.218)
  • smtp-prod03.osg.ufl.edu (128.227.74.219)
  • smtp-prod04.osg.ufl.edu (128.227.74.220)
  • smtp-prod05.osg.ufl.edu (128.227.74.125)
  • smtp-prod06.osg.ufl.edu (128.227.74.254)
  • TEST

  • virtual-smtp-test01.osg.ufl.edu (10.36.18.24)
  • smtp-test01.osg.ufl.edu (128.227.74.16)
  • smtp-test02.osg.ufl.edu (128.227.74.59)
Note: We recommend you maintain access to the test systems as well as production, as we do often ask for outside assistance in testing configuration changes.

 

Using smtp.ufl.edu as a smarthost / MX

Benefits of configuring your mail to go through smtp.ufl.edu include spam and virus scanning, as well as increased uptime and relability. In order to allow smtp.ufl.edu to handle your mail, contact EIO-Linux Infrastructure with a request to relay your mail through smtp.ufl.edu. Once that's complete, configure your MX records to mirror the university's MX record:

$dig -t MX ufl.edu +short
10 virtual-smtp-prod01.osg.ufl.edu.
20 smtp-prod06.osg.ufl.edu.
20 smtp-prod05.osg.ufl.edu.
20 smtp-prod04.osg.ufl.edu.
20 smtp-prod03.osg.ufl.edu.
20 smtp-prod02.osg.ufl.edu.
20 smtp-prod01.osg.ufl.edu.

 

Restrictions

Sending messages to non ufl.edu recipients is called relaying. In order to relay messages, one of the following must be true:

  • You authenticate to smtp.ufl.edu with your Gatorlink username and password.

  • You are logged into the campus Virtual private Network (VPN).

  • The computer you are using is on a managed network, i.e: a network maintained by CNS Network Services or by a University department. Dialup lines, walkup ports, and wireless conections are considered unmanaged, and require the authentication mentioned above.

Size

Email relayed by the SMTP server may not be larger than 35MB. Email is a very poor method to send data files because of the special encoding required to transmit the data in email form. A file sent through email will be approximatly 33% larger than if sent with conventional methods.

Number of Recipients

The maximum number of recipients that can be specified for email transiting the SMTP relay is 110.

Attachments

Many computer viruses and malware are spread via email attachments; to avoid this attachments with the following extensions will be blocked:

ade, adp, app, asd, asf, asx, bas, bat, chm, cmd, com, cpl, crt, dll, exe, fxp, hlp, hta, hto, inf, ini, ins, isp, jse?, lib, lnk, mdb, mde, msc, msi, msp, mst, ocx, pcd, pif, prg, reg, scr, sct, sh, shb, shs, sys, url, vb, vbe, vbs, vcs, vxd, wmd, wms, wmz, wsc, wsf, wsh

Relevent Internet RFCs

Following are the RFCs with which this service complies:

RFC ID
Topic
RFC974
MX routing
RFC976
UUCP mail format
RFC1123
Host requirements (modifies 821, 822, and 974)
RFC1344
Implications of MIME for Internet Mail Gateways
RFC1652
SMTP Service Extension for 8bit-MIMEtransport
RFC1869
SMTP Service Extensions (ESMTP spec)
RFC1870
SMTP Service Extension for Message Size Declaration
RFC1892
Multipart/Report Content Type for the Reporting of Mail System Administrative Messages
RFC1893
Enhanced Mail System Status Codes
RFC1894
An Extensible Message Format for Delivery Status Notifications
RFC1985
SMTP Service Extension for Remote Message Queue Starting
RFC2033
Local Mail Transfer Protocol (LMTP)
RFC2034
SMTP Service Extension for Returning Enhanced Error Codes
RFC2045
Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies
RFC2487
SMTP Service Extension for Secure SMTP over TLS
RFC2821
Simple Mail Transfer Protocol
RFC2822
Internet Message Format
RFC2920
SMTP Service Extension for Command Pipelining