In designing an e-mailer an important part is dimension especially the width of e-mail messages. As according to the screen resolutions, the email message that is fit on your computer screen immensely might need horizontal scrolling on someone other screen. This lead to loss of important content otherwise hidden by the scroll and missing your target audience. Mailer with width of 600 pixels or smaller is expected to be visible to all the readers.
Although it is possible to use a variable width instead of a fixed width to accommodate for all resolutions, variable widths do not hold items static within the message. Text and images will slide back and forth across the screen to accommodate screen size. Variable width email messages are not recommended.
Next important part of designing an e-mailer is images as they draw interest and help communicate your message. As bigger is the image as better a message is conveyed to the readers. There are several issues to consider when large images are used. Load time is one of the important aspects of image considerations in an e-mailer. Large images take more time to download than smaller images. The other important point of consideration for e-mail images is whether they are not disabled in an e-mail client. Following these points you can make your mailer attractive and reader friendly.