I use Thunderbird on my computers. 

It has numerous features that I like and it's free. Among the features are filters you can easily set to trash incoming junk mail.  You can easily add pictures to out going mail.

It has spell check.

It can have multiple accounts, yahoo, gmail, mail.com and many others.  You can set each one to retrieve mail at different schedules.

features: https://www.thunderbird.net/en-US/features/

https://www.thunderbird.net/en-US/download/?downloaded=True&download_channel=esr