Azure Blob Storage Provider

dotnet add package Zetian
dotnet add package Zetian.Storage.AzureBlob

using Zetian.Server;
using Zetian.Storage.AzureBlob.Extensions;

// Basic Azure Blob Storage setup
var server = new SmtpServerBuilder()
    .Port(25)
    .WithAzureBlobStorage(
        "DefaultEndpointsProtocol=https;AccountName=myaccount;AccountKey=mykey;")
    .Build();

await server.StartAsync();

// Azure AD authentication (recommended)
var server = new SmtpServerBuilder()
    .Port(25)
    .WithAzureBlobStorageAD(
        "mystorageaccount", // Storage account name only
        config =>
        {
            config.ContainerName = "smtp-messages";
            config.UseAzureAdAuthentication = true;
        })
    .Build();

var server = new SmtpServerBuilder()
    .Port(25)
    .WithAzureBlobStorage(
        "DefaultEndpointsProtocol=https;AccountName=myaccount;AccountKey=mykey;",
        config =>
        {
            config.ContainerName = "smtp-messages";
            
            // Access tiers
            config.AccessTier = BlobAccessTier.Cool;
            
            // Soft delete
            config.EnableSoftDelete = true;
            config.SoftDeleteRetentionDays = 7;
            
            // Performance
            config.CompressMessageBody = true;
            config.MaxMessageSizeMB = 100;
        })
    .Build();

// Automatic tier management based on age
// Hot -> Cool -> Archive

// Upload to Hot tier (immediate access)
await blobClient.SetAccessTierAsync(AccessTier.Hot);

// Move to Cool after 7 days (lower cost, slower access)
await blobClient.SetAccessTierAsync(AccessTier.Cool);

// Archive after 30 days (lowest cost, hours to retrieve)
await blobClient.SetAccessTierAsync(AccessTier.Archive);

// Lifecycle policy (automatic)
{
  "rules": [{
    "name": "MoveToArchive",
    "type": "Lifecycle",
    "definition": {
      "actions": {
        "baseBlob": {
          "tierToCool": { "daysAfterModificationGreaterThan": 7 },
          "tierToArchive": { "daysAfterModificationGreaterThan": 30 },
          "delete": { "daysAfterModificationGreaterThan": 365 }
        }
      }
    }
  }]
}

// Query messages using tags and metadata
var blobs = containerClient.GetBlobsAsync(
    traits: BlobTraits.Metadata | BlobTraits.Tags,
    prefix: "2024/01/");

await foreach (var blob in blobs)
{
    Console.WriteLine($"Message: {blob.Name}");
    Console.WriteLine($"Size: {blob.Properties.ContentLength}");
    Console.WriteLine($"From: {blob.Metadata["from"]}");
    Console.WriteLine($"Subject: {blob.Metadata["subject"]}");
}

// Search by tags
string query = @"""From"" = '[email protected]' AND ""ReceivedDate"" > '2024-01-01'";
var taggedBlobs = containerClient.FindBlobsByTagsAsync(query);