Email open rate is nothing but how many people opened your email from your subscribers. for example, for example if you send email to your hundred subscribers only twenty-five of them are opened then one percent use open rate of your email marketing. it is very important you have more percent open rate. to increase open rate,you have to send emails in regular intervals but if you send email continuously then your subscribers may block you or if you send emails occasionally then your subscriber may have forgot you he may doesn't open your email next time. for these reasons you have to find correct time interval to send your emails. there is another map twin increase open rate you should write a beautiful contents attract users to open your email choose email headings carefully or email subjects and pre-heading text.