Email.cshtml.cs

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Threading.Tasks;
using DotNetCoreRazor_MSGraph.Graph;
using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.RazorPages;
using Microsoft.Extensions.Logging;
using Microsoft.Graph;
using Microsoft.Identity.Web;

namespace DotNetCoreRazor_MSGraph.Pages
{
    [AuthorizeForScopes(ScopeKeySection = "DownstreamApi:Scopes")]
    public class EmailModel : PageModel
    {
        private readonly GraphEmailClient _graphEmailClient;
        
        [BindProperty(SupportsGet = true)]
        public string NextLink { get; set; }
        public IEnumerable<Message> Messages  { get; private set; }

        public EmailModel(GraphEmailClient graphEmailClient)
        {
            _graphEmailClient = graphEmailClient;
        }

        public async Task OnGetAsync()
        {
            var messagesPagingData = await _graphEmailClient.GetUserMessagesPage(NextLink); 
            Messages = messagesPagingData.Messages;
            NextLink = messagesPagingData.NextLink;
        }
    }
}

GraphEmailClient.cs

using System;
using System.IO;
using System.Collections;
using System.Collections.Generic;
using System.Threading.Tasks;
using Microsoft.Extensions.Logging;
using Microsoft.Graph;
using System.Linq;
using System.Net;
using System.Net.Http;

namespace DotNetCoreRazor_MSGraph.Graph
{
    public class GraphEmailClient
    {
        private readonly ILogger<GraphEmailClient> _logger;
        private readonly GraphServiceClient _graphServiceClient;

        public GraphEmailClient(ILogger<GraphEmailClient> logger, GraphServiceClient graphServiceClient)
        {
            _logger = logger;
            _graphServiceClient = graphServiceClient;
        }

        public async Task<IEnumerable<Message>> GetUserMessages()
        {
            try
            {
                var emails = await _graphServiceClient.Me.Messages
                            .Request()
                            .Select(msg => new
                            {
                                msg.Subject,
                                msg.BodyPreview,
                                msg.ReceivedDateTime
                            })
                            .OrderBy("receivedDateTime desc")
                            .Top(10)
                            .GetAsync();

                return emails.CurrentPage;
            }
            catch (Exception ex)
            {
                _logger.LogError($"Error calling Graph /me/messages: {ex.Message}");
                throw;
            }
        }

        public async Task<(IEnumerable<Message> Messages, string NextLink)> GetUserMessagesPage(
            string nextPageLink = null, int top = 10)
        {
            IUserMessagesCollectionPage pagedMessages;
            
            if (nextPageLink == null) 
            {
                // Get initial page of messages
                pagedMessages = await _graphServiceClient.Me.Messages
                        .Request()
                        .Select(msg => new
                        {
                            msg.Subject,
                            msg.BodyPreview,
                            msg.ReceivedDateTime
                        })
                        .Top(top)
                        .OrderBy("receivedDateTime desc")
                        .GetAsync();
            }
            else 
            {
                // Use the next page request URI value to get the page of messages
                var messagesCollectionRequest = 
                    new UserMessagesCollectionRequest(nextPageLink, _graphServiceClient, null);
                pagedMessages = await messagesCollectionRequest.GetAsync();
            }

            return (Messages: pagedMessages, NextLink: GetNextLink(pagedMessages));
        }

        private string GetNextLink(IUserMessagesCollectionPage pagedMessages) {
            if (pagedMessages.NextPageRequest != null)
            {
                // Get the URL for the next batch of records
                return pagedMessages.NextPageRequest.GetHttpRequestMessage().RequestUri?.OriginalString;
            }
            return null;
        }

    }
}