[PM-45051] Add m5 email templates

src/Core/MailTemplates/Handlebars/AdminConsole/OrganizationInvite/OrganizationInviteReminder1View.text.hbs

@@ -0,0 +1,7 @@
+{{#>TitleContactUsTextLayout}}
+{{OrganizationName}} invited you to join their organization vault on Bitwarden, giving you secure access to shared passwords, passkeys, and other sensitive items your team relies on.
+
+Your invite is still waiting! Accept it to get started.
+
+Accept invite: {{Url}}
+{{/TitleContactUsTextLayout}}

src/Core/MailTemplates/Handlebars/AdminConsole/OrganizationInvite/OrganizationInviteReminder2View.text.hbs

@@ -0,0 +1,9 @@
+{{#>TitleContactUsTextLayout}}
+It looks like you haven't joined the {{OrganizationName}} vault on Bitwarden yet.
+
+Accepting your invite gives you secure, encrypted access to the logins and other items your team has shared with you, so you can get to work without delay.
+
+If you have questions about this invite, reach out to your admin at {{OrganizationName}}.
+
+Accept invite: {{Url}}
+{{/TitleContactUsTextLayout}}

src/Core/MailTemplates/Handlebars/AdminConsole/OrganizationInvite/OrganizationInviteReminder3View.text.hbs

@@ -0,0 +1,7 @@
+{{#>TitleContactUsTextLayout}}
+This is your final reminder to join the {{OrganizationName}} vault on Bitwarden. If you do not accept, your access will expire and you'll need to request a new invite from your admin to gain access.
+
+Accept now to keep your access to shared logins, passkeys, and secure notes uninterrupted.
+
+Accept invite: {{Url}}
+{{/TitleContactUsTextLayout}}

src/Core/MailTemplates/Mjml/emails/AdminConsole/OrganizationInvite/organization-invite-reminder-1.mjml

@@ -0,0 +1,48 @@
+<mjml>
+  <mj-head>
+    <mj-include path="../../../components/head.mjml" />
+    <mj-include path="../components/admin-console-head.mjml" />
+  </mj-head>
+
+  <mj-body css-class="border-fix">
+    <!-- Blue Header Section -->
+    <mj-wrapper css-class="border-fix" padding="20px 20px 10px 20px">
+      <mj-bw-ac-hero
+        img-src="https://assets.bitwarden.com/email/v1/ac-spot-enterprise.png"
+        title="{{OrganizationName}} invited you to join them on Bitwarden"
+        button-text="<b>Accept invite</b>"
+        button-url="{{Url}}"
+      />
+    </mj-wrapper>
+
+    <!-- Main Content -->
+    <mj-wrapper padding="5px 20px 8px 20px">
+      <mj-section background-color="#fff" padding="10px 10px 16px 10px">
+        <mj-column>
+          <mj-text
+            css-class="ac-text"
+            padding="15px 15px 0px 15px"
+          >
+            <b>{{OrganizationName}}</b> invited you to join their organization vault on
+            Bitwarden, giving you secure access to shared passwords, passkeys,
+            and other sensitive items your team relies on.
+          </mj-text>
+          <mj-text
+            css-class="ac-text"
+            padding="15px 15px 0px 15px"
+          >
+            Your invite is still waiting! Accept it to get started.
+          </mj-text>
+        </mj-column>
+      </mj-section>
+    </mj-wrapper>
+
+    <!-- Learn More Section -->
+    <mj-wrapper padding="8px 20px 10px 20px">
+      <mj-bw-ac-learn-more-footer />
+    </mj-wrapper>
+
+    <!-- Footer -->
+    <mj-include path="../../../components/footer.mjml" />
+  </mj-body>
+</mjml>

src/Core/MailTemplates/Mjml/emails/AdminConsole/OrganizationInvite/organization-invite-reminder-2.mjml

@@ -0,0 +1,56 @@
+<mjml>
+  <mj-head>
+    <mj-include path="../../../components/head.mjml" />
+    <mj-include path="../components/admin-console-head.mjml" />
+  </mj-head>
+
+  <mj-body css-class="border-fix">
+    <!-- Blue Header Section -->
+    <mj-wrapper css-class="border-fix" padding="20px 20px 10px 20px">
+      <mj-bw-ac-hero
+        img-src="https://assets.bitwarden.com/email/v1/ac-spot-enterprise.png"
+        title="{{OrganizationName}} invited you to join them on Bitwarden"
+        button-text="<b>Accept invite</b>"
+        button-url="{{Url}}"
+      />
+    </mj-wrapper>
+
+    <!-- Main Content -->
+    <mj-wrapper padding="5px 20px 8px 20px">
+      <mj-section background-color="#fff" padding="10px 10px 16px 10px">
+        <mj-column>
+          <mj-text
+            css-class="ac-text"
+            padding="15px 15px 0px 15px"
+          >
+            It looks like you haven't joined the <b>{{OrganizationName}}</b> vault
+            on Bitwarden yet.
+          </mj-text>
+          <mj-text
+            css-class="ac-text"
+            padding="15px 15px 0px 15px"
+          >
+            Accepting your invite gives you secure, encrypted access to the
+            logins and other items your team has shared with you, so you can
+            get to work without delay.
+          </mj-text>
+          <mj-text
+            css-class="ac-text"
+            padding="15px 15px 0px 15px"
+          >
+            If you have questions about this invite, reach out to your admin
+            at {{OrganizationName}}.
+          </mj-text>
+        </mj-column>
+      </mj-section>
+    </mj-wrapper>
+
+    <!-- Learn More Section -->
+    <mj-wrapper padding="8px 20px 10px 20px">
+      <mj-bw-ac-learn-more-footer />
+    </mj-wrapper>
+
+    <!-- Footer -->
+    <mj-include path="../../../components/footer.mjml" />
+  </mj-body>
+</mjml>

src/Core/MailTemplates/Mjml/emails/AdminConsole/OrganizationInvite/organization-invite-reminder-3.mjml

@@ -0,0 +1,50 @@
+<mjml>
+  <mj-head>
+    <mj-include path="../../../components/head.mjml" />
+    <mj-include path="../components/admin-console-head.mjml" />
+  </mj-head>
+
+  <mj-body css-class="border-fix">
+    <!-- Blue Header Section -->
+    <mj-wrapper css-class="border-fix" padding="20px 20px 10px 20px">
+      <mj-bw-ac-hero
+        img-src="https://assets.bitwarden.com/email/v1/ac-spot-enterprise.png"
+        title="{{OrganizationName}} invited you to join them on Bitwarden"
+        button-text="<b>Accept invite</b>"
+        button-url="{{Url}}"
+      />
+    </mj-wrapper>
+
+    <!-- Main Content -->
+    <mj-wrapper padding="5px 20px 8px 20px">
+      <mj-section background-color="#fff" padding="10px 10px 16px 10px">
+        <mj-column>
+          <mj-text
+            css-class="ac-text"
+            padding="15px 15px 0px 15px"
+          >
+            This is your final reminder to join the <b>{{OrganizationName}}</b>
+            vault on Bitwarden. If you do not accept, your access will expire
+            and you'll need to request a new invite from your admin to gain
+            access.
+          </mj-text>
+          <mj-text
+            css-class="ac-text"
+            padding="15px 15px 0px 15px"
+          >
+            Accept now to keep your access to shared logins, passkeys, and
+            secure notes uninterrupted.
+          </mj-text>
+        </mj-column>
+      </mj-section>
+    </mj-wrapper>
+
+    <!-- Learn More Section -->
+    <mj-wrapper padding="8px 20px 10px 20px">
+      <mj-bw-ac-learn-more-footer />
+    </mj-wrapper>
+
+    <!-- Footer -->
+    <mj-include path="../../../components/footer.mjml" />
+  </mj-body>
+</mjml>

src/Core/Platform/Mail/HandlebarsMailService.cs

@@ -431,6 +431,45 @@ public async Task SendUpdatedOrganizationInviteEmailsAsync(OrganizationInvitesIn
         await EnqueueMailAsync(messageModels);
     }
 
+    public async Task SendOrganizationInviteReminderEmailsAsync(OrganizationInvitesInfo orgInvitesInfo, int reminderNumber)
+    {
+        var messageModels = orgInvitesInfo.OrgUserTokenPairs.Select(orgUserTokenPair =>
+        {
+            Debug.Assert(orgUserTokenPair.OrgUser.Email is not null);
+
+            var organizationName = CoreHelpers.PreventEmailAutoLinking(orgInvitesInfo.OrganizationName);
+
+            var (subject, templateName) = reminderNumber switch
+            {
+                1 => ($"Reminder: You're invited to join {orgInvitesInfo.OrganizationName} on Bitwarden",
+                    "AdminConsole.OrganizationInvite.OrganizationInviteReminder1View"),
+                2 => ($"Don't miss out: Your {orgInvitesInfo.OrganizationName} invite is still waiting",
+                    "AdminConsole.OrganizationInvite.OrganizationInviteReminder2View"),
+                3 => ($"Last chance: Your {orgInvitesInfo.OrganizationName} invite is about to expire",
+                    "AdminConsole.OrganizationInvite.OrganizationInviteReminder3View"),
+                _ => throw new ArgumentOutOfRangeException(nameof(reminderNumber), reminderNumber,
+                    "Reminder number must be 1, 2, or 3.")
+            };
+
+            var url = BuildInvitationUrl(orgInvitesInfo, orgUserTokenPair.OrgUser, orgUserTokenPair.Token);
+            var expirationDate = $"{orgUserTokenPair.Token.ExpirationDate.ToLongDateString()} {orgUserTokenPair.Token.ExpirationDate.ToShortTimeString()} UTC";
+
+            var message = CreateDefaultMessage(subject, orgUserTokenPair.OrgUser.Email);
+
+            return new MailQueueMessage(message, templateName, new
+            {
+                OrganizationName = organizationName,
+                Email = orgUserTokenPair.OrgUser.Email,
+                ExpirationDate = expirationDate,
+                Url = url,
+                InviterEmail = orgInvitesInfo.InviterEmail,
+                CurrentYear = DateTime.UtcNow.Year.ToString()
+            });
+        });
+
+        await EnqueueMailAsync(messageModels);
+    }
+
     public async Task SendUpdatedOrganizationConfirmedEmailAsync(Organization organization, string userEmail, bool accessSecretsManager = false)
     {
         var organizationName = organization.DisplayName();

src/Core/Platform/Mail/IMailService.cs

@@ -73,6 +73,12 @@ Task SendTrialInitiationSignupEmailAsync(
     /// <param name="orgInvitesInfo">The information required to send the organization invites.</param>
     Task SendOrganizationInviteEmailsAsync(OrganizationInvitesInfo orgInvitesInfo);
     Task SendUpdatedOrganizationInviteEmailsAsync(OrganizationInvitesInfo orgInvitesInfo);
+    /// <summary>
+    /// Sends a reminder email to the members of an organization who have not yet accepted their invite.
+    /// </summary>
+    /// <param name="orgInvitesInfo">The information required to send the organization invite reminders.</param>
+    /// <param name="reminderNumber">Which reminder is being sent: 1, 2, or 3.</param>
+    Task SendOrganizationInviteReminderEmailsAsync(OrganizationInvitesInfo orgInvitesInfo, int reminderNumber);
     Task SendOrganizationMaxSeatLimitReachedEmailAsync(Organization organization, int maxSeatCount, IEnumerable<string> ownerEmails);
     Task SendOrganizationAutoscaledEmailAsync(Organization organization, int initialSeatCount, IEnumerable<string> ownerEmails);
     Task SendOrganizationAcceptedEmailAsync(Organization organization, string userIdentifier, IEnumerable<string> adminEmails, bool hasAccessSecretsManager = false);

src/Core/Platform/Mail/NoopMailService.cs

@@ -96,6 +96,11 @@ public Task SendUpdatedOrganizationInviteEmailsAsync(OrganizationInvitesInfo org
         return Task.FromResult(0);
     }
 
+    public Task SendOrganizationInviteReminderEmailsAsync(OrganizationInvitesInfo orgInvitesInfo, int reminderNumber)
+    {
+        return Task.FromResult(0);
+    }
+
     public Task SendOrganizationUserRevokedForTwoFactorPolicyEmailAsync(string organizationName, string email) =>
         Task.CompletedTask;
 

test/Core.Test/Services/HandlebarsMailServiceTests.cs

@@ -4,6 +4,7 @@
 using Bit.Core.Auth.Entities;
 using Bit.Core.Auth.Enums;
 using Bit.Core.Auth.Models.Business;
+using Bit.Core.Billing.Enums;
 using Bit.Core.Entities;
 using Bit.Core.Models.Mail;
 using Bit.Core.Platform.Mail.Delivery;
@@ -567,6 +568,104 @@ public void GetCloudVaultSubscriptionUrl_ResolvesPerRegion(string cloudRegion, s
         Assert.StartsWith(expectedVaultBase, result);
     }
 
+    [Theory]
+    [InlineData(1, "Reminder: You're invited to join Acme.Corp on Bitwarden", "OrganizationInviteReminder1View")]
+    [InlineData(2, "Don't miss out: Your Acme.Corp invite is still waiting", "OrganizationInviteReminder2View")]
+    [InlineData(3, "Last chance: Your Acme.Corp invite is about to expire", "OrganizationInviteReminder3View")]
+    public async Task SendOrganizationInviteReminderEmailsAsync_SendsCorrectSubjectAndTemplate(
+        int reminderNumber, string expectedSubject, string expectedTemplateName)
+    {
+        // Arrange
+        _mailEnqueuingService
+            .EnqueueManyAsync(Arg.Any<IEnumerable<IMailQueueMessage>>(), Arg.Any<Func<IMailQueueMessage, Task>>())
+            .Returns(callInfo => Task.WhenAll(
+                callInfo.Arg<IEnumerable<IMailQueueMessage>>().Select(callInfo.Arg<Func<IMailQueueMessage, Task>>())));
+
+        var organization = new Organization { Id = Guid.NewGuid(), Name = "Acme.Corp", PlanType = PlanType.Free };
+        var orgUser = new OrganizationUser
+        {
+            Id = Guid.NewGuid(),
+            OrganizationId = organization.Id,
+            Email = "member@example.com"
+        };
+        var token = new ExpiringToken("test_token", DateTime.UtcNow.AddDays(5));
+
+        var orgInvitesInfo = new OrganizationInvitesInfo(
+            organization,
+            orgSsoEnabled: false,
+            orgSsoLoginRequiredPolicyEnabled: false,
+            orgUserTokenPairs: new[] { (orgUser, token) },
+            orgUserHasExistingUserDict: new Dictionary<Guid, bool> { { orgUser.Id, false } },
+            inviterEmail: "inviter@example.com");
+
+        // Act
+        await _sut.SendOrganizationInviteReminderEmailsAsync(orgInvitesInfo, reminderNumber);
+
+        // Assert
+        await _mailDeliveryService.Received(1).SendEmailAsync(Arg.Is<MailMessage>(m =>
+            m.ToEmails.Contains("member@example.com") &&
+            m.Subject == expectedSubject &&
+            m.HtmlContent.Contains("Acme.&#8204;Corp") &&
+            m.Category == $"AdminConsole.OrganizationInvite.{expectedTemplateName}"));
+    }
+
+    [Fact]
+    public async Task SendOrganizationInviteReminderEmailsAsync_MultipleMembers_SendsOneEmailPerMember()
+    {
+        // Arrange
+        _mailEnqueuingService
+            .EnqueueManyAsync(Arg.Any<IEnumerable<IMailQueueMessage>>(), Arg.Any<Func<IMailQueueMessage, Task>>())
+            .Returns(callInfo => Task.WhenAll(
+                callInfo.Arg<IEnumerable<IMailQueueMessage>>().Select(callInfo.Arg<Func<IMailQueueMessage, Task>>())));
+
+        var organization = new Organization { Id = Guid.NewGuid(), Name = "Acme Corp", PlanType = PlanType.Free };
+        var orgUser1 = new OrganizationUser { Id = Guid.NewGuid(), OrganizationId = organization.Id, Email = "one@example.com" };
+        var orgUser2 = new OrganizationUser { Id = Guid.NewGuid(), OrganizationId = organization.Id, Email = "two@example.com" };
+        var token = new ExpiringToken("test_token", DateTime.UtcNow.AddDays(5));
+
+        var orgInvitesInfo = new OrganizationInvitesInfo(
+            organization,
+            orgSsoEnabled: false,
+            orgSsoLoginRequiredPolicyEnabled: false,
+            orgUserTokenPairs: new[] { (orgUser1, token), (orgUser2, token) },
+            orgUserHasExistingUserDict: new Dictionary<Guid, bool> { { orgUser1.Id, false }, { orgUser2.Id, true } });
+
+        // Act
+        await _sut.SendOrganizationInviteReminderEmailsAsync(orgInvitesInfo, 1);
+
+        // Assert
+        await _mailDeliveryService.Received(1).SendEmailAsync(Arg.Is<MailMessage>(m => m.ToEmails.Contains("one@example.com")));
+        await _mailDeliveryService.Received(1).SendEmailAsync(Arg.Is<MailMessage>(m => m.ToEmails.Contains("two@example.com")));
+    }
+
+    [Fact]
+    public async Task SendOrganizationInviteReminderEmailsAsync_RequireSsoOrganization_BuildsUrlWithSsoIdentifier()
+    {
+        // Arrange
+        _mailEnqueuingService
+            .EnqueueManyAsync(Arg.Any<IEnumerable<IMailQueueMessage>>(), Arg.Any<Func<IMailQueueMessage, Task>>())
+            .Returns(callInfo => Task.WhenAll(
+                callInfo.Arg<IEnumerable<IMailQueueMessage>>().Select(callInfo.Arg<Func<IMailQueueMessage, Task>>())));
+
+        var organization = new Organization { Id = Guid.NewGuid(), Name = "Acme Corp", PlanType = PlanType.Free, Identifier = "acme-sso" };
+        var orgUser = new OrganizationUser { Id = Guid.NewGuid(), OrganizationId = organization.Id, Email = "member@example.com" };
+        var token = new ExpiringToken("test_token", DateTime.UtcNow.AddDays(5));
+
+        var orgInvitesInfo = new OrganizationInvitesInfo(
+            organization,
+            orgSsoEnabled: true,
+            orgSsoLoginRequiredPolicyEnabled: true,
+            orgUserTokenPairs: new[] { (orgUser, token) },
+            orgUserHasExistingUserDict: new Dictionary<Guid, bool> { { orgUser.Id, false } });
+
+        // Act
+        await _sut.SendOrganizationInviteReminderEmailsAsync(orgInvitesInfo, 1);
+
+        // Assert
+        await _mailDeliveryService.Received(1).SendEmailAsync(Arg.Is<MailMessage>(m =>
+            m.HtmlContent.Contains("orgSsoIdentifier=acme-sso")));
+    }
+
     [Theory]
     [InlineData(nameof(HandlebarsMailService.SendEmergencyAccessConfirmedEmailAsync))]
     [InlineData(nameof(HandlebarsMailService.SendEmergencyAccessRecoveryApproved))]