A perfectly controlled email campaign relies on a correct routing of mails to their recipients. Thisdeliverability Thus guaranteeing access in inbox, for a strong ROI of the emailing strategy.
An optimized routing involves a careful composition of mails, with the aim of avoiding their assimilation to "spams". One must keep in mind that any mail using the techniques of spammers may end up in the trash before it has even been seen by its recipient. The subject of the e-mail must not be empty, be written in capital letters or contain words of a sexual nature. It is better to avoid repetitions, business formulas as well as special characters. The body of the mail must use a normal font size, but also present a good balance between image and text. Finally, attachments as well as priority "high" are frowned upon.
Optimization of deliverability has a technical aspect. As a general rule, an anti-spam filter considers suspicious any mailing with a return rate greater than 20%. Hence the importance of avoiding outdated or invalid address files. Each email campaign must allow the removal from the list the email addresses presenting an error message, in order to reduce the rate of return. Second, antispam filtering favors SMTP servers that follow the rules for bulk mailings. Thus, it is better to keep your distances with shared hosting, especially if other websites use it to spam. Finally, the IP address used for sending must match that of the Web site concerned, in order to overcome the Reverse DNS protocols.