The simplest solution is to try rebuilding your Mail folder. El Capitan Mail Issues: 10 Ways To Fix ThemĪpple will automatically do this for your with the Mail Settings Lookup tool. The precise cause of the problem usually depends on your specific setup but if you try going through these fixes, one of them should get mail working on El Capitan again. Mail issues are a common problem with new versions of OS X and we’ve been through this many times before so we’ve looked at the most common solutions to bugs such as Mail not opening, crashing, refusing to recognize accounts or simply freezing when opening or trying to send and receive email.
However, this still hasn’t fixed the problems for many users who have coined the name “El Crapitan” for the various problems and bugs that have plagued OS X 10.11. We recommend before proceeding that you install this update first to see if it fixes Mail which you can install by going to the Mac App Store and selecting “Updates” at the top.
On October 21st Apple released the El Capitan 10.11.1 update which claimed to have fixed Apple Mail problems with outgoing server issues and message display problems. There are still various El Capitan Mail issues that some people are having including mail not sending in El Capitan, mail not being received and many more frustrating bugs.
