StandManager/StandManager.MailProcessor/MailProcessor.cs

using StandManager.Domain.DTO;
using StandManager.Service.Interfaces;
using StandManager.Service.Resolver;

public class MailProcessor
{
    private readonly IManagerService _managerService;
    private readonly EmailConfig _config;
    private readonly IMailProcessorResolver _resolver;

    public MailProcessor(IManagerService managerService, EmailConfig config, IMailProcessorResolver resolver)
    {
        _managerService = managerService;
        _config = config;
        _resolver = resolver;
    }

    public async Task Process()
    {
        var list = await _managerService.MailQueueService.RicercaQueryable(x =>
            x.Eliminato == false && x.Sent == false && string.IsNullOrEmpty(x.Error), solaLettura:false);
        
        using var httpClient = new HttpClient();
        foreach (var mailQueueByFrom in list.GroupBy(x => x.From))
        {
            var processor = _resolver.Resolve(mailQueueByFrom.Key);

            await processor.ProcessAsync(mailQueueByFrom.ToList(), _config, httpClient);
        }
        
        var a = list;
    }
}