"My subscribers aren't receiving my emails!"
Typically, when your subscribers don't see your email campaigns in their inboxes, it's because of SPAM filters. If your subscribers still don't see your campaign in their spam, junk or 'other' folder, there are a few things you can do.
Is a specific subscriber not receiving your emails? You can ask them to add your "From"-email to their contact list or address book.
If your "From"-email is in their address book, you should ask them to check their spam filter settings to be sure that your content and/or address isn't blocked.
Are your subscribers using free email services like Gmail, Yahoo or Hotmail? These providers throttle delivery, which can sometimes result in emails taking 24 hours to be delivered.
Has the campaign actually been sent? There can sometimes be server hick-ups, and you can be put in a delivery-queue. This is especially prevalent if you're sending from a third-party server like MailChimp, and not using a dedicated IP.
Could there be an internal firewall causing your emails not to be delivered? Some domains don't like seeing emails going to and from the same domain, via a third party. For instance, you may be sending an internal company newsletter from firstname.lastname@example.org to email@example.com. With large corporate filters, emails like these can seem suspicious and will be blocked. In this case, safelisting your email marketing software might solve this.
If you are using your own dedicated IP, and your subscribers are still not receiving your emails, this is most likely due to misconfigured or missing DNS, DKIM or SPF records, or blocked IP address.
To verify that you've setup your SPF correctly, I recommend using MX Toolbox: https://mxtoolbox.com/