Choose Email License For Free

Based on the research, the newly created unlicensed user can access the public SharePoint site(Everyone except external users can access it directly) and can't access the private SharePoint site directly. The unlicensed user in Office 365 can't use most of the service: OneDrive, Office online, Exchange online etc.

1 Use Microsoft Office Mobile Apps You can make use of the Office Mobile app on your smartphones like Windows Phone, iPhone and Android for free. The Mobile app includes major Microsoft Office utilities like Word, PowerPoint, Excel, Calendar, OneDrive, OneNote, SharePoint, and Mail.

A shared mailbox in Office 365 is free and does not require a license. For example, emails that are always forwarded or delegated do not require a full user license. Instead, licensed user accounts can be granted either forwarding from the shared mailbox and/or delegation to the shared mailbox.

Office 365 OutlookYou do not need a separate license of Microsoft Exchange Server to send, receive or manage mail from your Microsoft Webmail account. You can also use Office 365 Outlook or Outlook.com to access and manage your email from other providers, such as Gmail or Yahoo Mail.

You do need a license to use a locally installed Outlook application. Some Office 365 plans include licenses for locally installed Office applications, including Outlook.

Microsoft 365 E3 license costs $32.00 per user per month with an annual commitment and includes: Microsoft 365 Apps; Powerpoint, Word, Excel, OneNote, Publisher (PC only), and Access (PC only) Email and calendar; Outlook, Exchange, and Bookings. Social and Intranet; SharePoint and Yammer.

Email licenses are free. Typically you would assign this to end users that would only need to report progress without needing to review the full work plan or use other modules like issues\\requests\\etc. Hope that answers your questions. Roni.