I have been using yahoo mail for quite some time. However, I am not really impressed with their product or their improvements. Since 2013 I had issues regarding hacking, their advertisement placement is very frustrating, their platform is very slow and these factors are some to name a few. An alternative email platform that I would recommend and I am currently using is Milfence which offers an secure email service offering end to end encryption and a protected platform.
Gmail - Gmail is available across all your devices Android, iOS, and desktop devices. Sort, collaborate or call a friend without leaving your inbox.
Virtru - Virtru is your data privacy force field, wrapping and protecting emails and files wherever they're shared. Easy-to-use data security software for business. People also askIs Virtru Hipaa compliant?
Microsoft Outlook - Organize your world. Outlook’s email and calendar tools help you communicate, stay on top of what matters, and get things done.
Paubox - Paubox provides HIPAA compliant email encryption without the hassle of extra steps.
Zoho Mail - Zoho Mail is a secure, encrypted, and enterprise-ready email solution, a suite of apps tailor-made for your organization's needs.
Proofpoint Email Encryption - As email is the preferred medium for business communications, preventing confidential information from being leaked in outbound email messages must be a top priority in order to lower the risk of a data breach.