While there's no doubt a well designed page of HTML with graphics can make a solid impact, sadly not everyone will get to view your campaign as it was intended, if at all. Emails are at the mercy of firewalls, filters and clients' permission settings.
Most of the major email clients such as Outlook and Gmail have image viewing turned off by default. A small percentage of clients do not even permit HTML based email to get through at all, and for the rest that do it's been shown that as much as 30% of recipients are not actually aware images are being blocked.
Plain text email, although less appealing has a much better chance of getting through SPAM filters than HTML. For this reason, we recommend your email is always accompanied by a plain text version of your message. Our software will generate a plain text version automatically which can be edited as well.
Several other factors can trigger the attention of SPAM filters, even when plain text is used. Read this short list of points to help stear your next campaign past the pitfalls of email filtering.