We went back to school on Tuesday for our webcast ABCs of ISPs. Our presenters, Kristin Ferraro and Ryan Harris, not only shared some information on how to get delivered to the major internet service providers (ISPs), they also answered some great questions we were receiving live. Since everyone wasn’t able to see all those questions asked behind-the-scenes, we thought we’d pick a few of them to showcase below: What rate of spam could trigger Gmail to filter out messages? There are several factors that can go into Gmail taking the action to filter out messages. We believe it involves engagement levels, like message opens or clicks on links. Gmail most likely also takes into account those that are not engaging in emails. If the majority of emails are not being engaged, then emails could be filtered as spam. How do we find those inactive users/subscribers using SendGrid? What SendGrid users should do is make sure that click and open tracking is active. Then look at email stats either on the SendGird account UI or through the Event Webhook to see all the emails that have been opened in the last 6 months. Those are the most engaged recipients. Any address that hasn’t clicked or opened a message should be removed from the recipient list. The SendGrid support team can easily help customers find this information. Support@sendgrid.com is the easiest way to reach them. How large of an embedded .jpeg (pixels or bytes) is appropriate for a marketing email? It depends on image to text ratio. One tool that can be used to test email is mail-tester.com. Mail can be sent to their system and it will evaluate if image to text ratio is off. We occasionally get complaints from our users that they are not receiving transactional mail from us. We see no penalties (spam, block, bounce) in our SendGrid dashboard and the email log shows it was delivered. What’s next? When SendGrid reports that an email was delivered, it means that the recipient domain gave a 250OK response, which means they accepted the message. This response doesn’t necessarily mean that the email was delivered to the inbox. It could be the recipient domain accepted the mail, then passed the mail through their own filters and filtered the mail as spam, or dropped the mail all together. We would recommend reaching out to the admin of the recipient domain to see if they can dig deeper into why the message was not delivered. If I ever did get blacklisted, couldn’t I just get another IP address from you? We don’t recommend “just getting a new IP,” because Google and other ISPs actually put more weight on domain reputation. The first step we suggest is to try and remove the blacklisting and/or change list management practices. Do you recommend users to manually filter through email lists to remove emails? Ideally, the best way to filter a list of emails is using a confirmed opt-in. This way, SendGrid users ensure emails are up-to-date when they sign up for a service. If users have old lists, we suggest removing addresses which have not engaged in emails recently, or send a reconfirmation campaign asking for recipients to click on a link within the message to confirm they are still interested in receiving future email. If you have additional questions, SendGrid Support is always happy to work with customers to find solutions to their issues. Be sure to check out the entire webcast, or if you attended and want more then download the guide!