1) From name is not always displayed
AOL only shows users the from address, not the from name. Therefore what if you have a from address with the domain part made up of your email service provider? Clearly your average recipient is going to be suspicious of this type of email address, particularly as they have been told by AOL so many times in the media about phishing emails.

Also if you have an email address such as no-reply@yourdomain.com it is hardly a warm and inspiring address that encourages them to open the email.

2) Email client whitelists
Most major email clients & web-based email providers give their users the opportunity to “whitelist” addresses with a click of a button. This prevents this address being filtered as junk mail and ensures images are displayed. Adding your address to their address book will also achieve this in numerous email clients. Clearly then if you keep changing your address, or if your supplier dynamically generates an address each time the clients whitelisting will fail.

3) Domain Blacklisting
It is not just IP addresses that can get blacklisted but whole domains. It is unlikely that your domain will ever get blacklisted if you are sending genuine permission based emails. However your supplier who is sending millions of emails a day through there ‘From’ domain they make you use could be blacklisted. Therefore make sure you choose email marketing software that enables you to put any address in.

In addition other similar domains could cause your email to be rejected. For example an Emailcenter client was using a .org.uk domain. An overseas spammer who was blacklisted owned the same .org domain. The blacklists filtering rules did not distinguish between .org and .org.uk domains and therefore rejected the email. Upon contact with the blacklist owner the blocking was immediately rectified.

4) Spam filter scoring
Spam filters use your from address as a means of determining how likely it is that you are a spammer. For example these types of addresses might be frowned upon by some filters:
- noreply@domain.com
- 12345@domain.com
- sales@domain.com

These are typical of a spammers address and therefore treated as such by the filters.

5) Sender ID Records
No doubt you will have received a phishing email in the past from somewhere claiming to be your bank and asking for your login details. Surprisingly these emails get results for the senders and people do hand over their login details that get abused.

Therefore ISP’s are keen to find ways of filtering these emails. As most phishing attacks mask the from address so it looks like it has been sent from the real bank, one method is to check that the server sending the email is the same server that holds the domain. This in itself is a crude method as all large organisations have systems that send email from outside of their domain. A typical example of this would be order confirmations from the clients e-commerce server.

Therefore a technology called Sender ID has developed and is used by the likes of Hotmail. Sender ID is a record that any company can publish that lists what IP addresses are allowed to send email using their domain in the from address. ISP’s can then check any email they receive to see if the from domain matches the IP addresses held in their Sender ID record.

Not all email that fails this check gets junked but it does add to your spam score and make your email more likely to get junked.