Staff Email - Email Restrictions

This page outlines the email restriction policies in place on the Exchange email service for College staff.

In an effort to combat the large amount of virus and spam emails targeted at College, all incoming emails are subject to a number of security checks. Only email messages which pass these checks can be received. There are other technical restrictions in place such as the size of attachments. Sometimes a legitimate email may be blocked due to these restrictions. In this case the user will have to resend the message, altered in the appropriate way.

The following email restrictions are in place:

Viruses

Emails containing known viruses are automatically blocked.

Attachment Types - File Extensions

All common extensions such as .doc .xls .ppt .pdf are permitted. However files ending with .exe .bat .cmd .vbs .com .scr .pif .dll .cpl .hta are all blocked for security reasons.

Container files such as .bin .eml .gzip .zip .jar .rar .tar .uue are permitted but other container files may be blocked if they contain the restricted file types listed above.

Size of Attachment

There is an upper limit of 15MB on the size of email attachments. Anything larger is blocked. This type of restriction is an industry standard on many email servers. If you wish to send a larger file you may consider using the HEAnet FileSender service.

Number of Emails Sent per Hour

There is a limit in terms of how many emails may be sent per hour from any one account. This limit is 300 emails per hour during working hours and 150 outside of those; this could be 300 individual emails or 1 email sent to 300 recipients. This limit does not apply when using mailing lists, only if multiple separate email address are specified when sending the email. Exceeding this limit will block your ability to send email for 24 hours.  To circumvent this, if you wish to send emails to more than the relevant limit you should send in smaller batches per hour. For example, if sending to a collection of 1000 e-mail addresses please have break it into 4 batches of 250 recipients and send to one batch per hour over the course of the day.

SPAM Email

Emails with subject lines which look like SPAM are automatically rejected.

Unknown Senders

Email from nonexistent internet domains e.g. jbloggs@xyzwstrty.com is rejected.

Blacklists

Any email from internet domains which have been blacklisted is rejected.