Email service providers like Yahoo and Hotmail use junk and adult content filters to protect users from spam.

Here is the Microsoft description of what the junk words filter looks for and where they filter looks for them:

From:

• First eight characters of From are digits
• From contains 'sales@'
• From contains 'success'
• From contains 'success@'
• From contains 'mail@'
• From contains '@public'
• From contains '@savvy'
• From contains 'profits@'
• From contains 'hello@'

To:

• To contains 'friend@'
• To contains 'public@'
• To contains 'success@'

Subjects:

• Subject contains a advertisement
• Subject contains '!' & '£'
• Subject contains '!' & 'free'
• Subject contains '££'

Body:

• Body contains 'money back'
• Body contains 'cards accepted'
• Body contains 'removal instructions'
• Body contains 'extra income'
• Body contains '000' & '!!'
• Body contains '£'
• Body contains 'Dear friend'
• Body contains 'for free?'
• Body contains 'for free!'
• Body contains 'Guarantee'
• Body contains 'satisfaction' or 'absolute'
• Body contains 'more info' & 'visit'
• Body contains 'special promotion'
• Body contains one-time mail'
• Body contains '££'
• Body contains 'order today'
• Body contains 'order now!'
• Body contains 'money-back guarantee'
• Body contains '100% satisfied'
• Body contains 'mlm'
• Body contains '@mlm'
• Body contains '///////////////'
• Body contains 'cheque or money order'

Email formats

HTML emails are the most popular format used by Online Marketers. They create a more distinctive look, have greater functionality, are more polished and have stronger branding.

But unfortunately:

• Not all email software can read HTML
• Some users don't want to read HTML emails and switch of this facility
• HTML emails are usually larger in size and can meet the software's limit (25k max)
• Most often has to be read while connected to the internet
• Forwarding not always possible
• Can be blocked by corporate firewalls

If your recipient's preferences are not known it is best practise to send a Plain Text email along side your HTML copy. If their email software does not except HTML emails the Plain Text version will enter the inbox instead. Within your Plain Text email you should have a link to a landing page that will display your HTML email version.

Frequency and Timing

Before you start to think about sending out newsletters you need to think about how frequent you are going to send them out.

It is generally believed anything more then twice a month is to frequent unless the reader has signed up more updates. A point to note regarding frequency is the more frequent the email is, the shorter it should be.

There are different theories about the best days to send out emails. This varies with each industry. It is recommended that B2B emails are best sent between Tuesday and Thursday morning. The reason for this is people are usually still in weekend mode on Mondays and by Tuesdays they are ready to work. Fridays are regarded as a wine down day and people mentally check out for the weekend. While B2C entertainment emails is best sent over the weekend.

You can always ask your subscribers how often and when they would like to receive emails at the time of registration. It is recommended to always A/B test each email you send to get the best response rate.