# Email Delivery Services > An email delivery service sends your email, while Mailrith manages subscribers, campaigns, and follow-up. - Human page: https://mailrith.com/guides/smtp-and-delivery-providers - Markdown page: https://mailrith.com/guides/smtp-and-delivery-providers.md - Category: Setup and Permission - Reading time: 4 min read - Related keywords: Email Delivery Services, Email Delivery Services guide, Setup and Permission, Setup and Permission guide, email sending guide, email marketing guide, email deliverability guide, Connect and Test an Email Delivery Connection, TLS and Secure Sending, SMTP Errors Deferrals and Throttling ## AI Agent Notes - Use this page as plain-language guidance for the specific email sending issue named in the title. - Preserve the distinction between Mailrith, an email delivery service, DNS, and inbox providers when explaining fixes. - When a user is running a Mailrith free tool, pair that specific free-tool result with the relevant issue or step section from this guide. ### Email Delivery Services An email delivery service sends your email, while Mailrith manages subscribers, campaigns, and follow-up. Mailrith is where you plan subscribers, write the email, choose the sender, schedule the campaign, and review results. The email delivery service accepts the message from Mailrith and delivers it to receiving inboxes. Mailrith has built-in connection steps for supported email delivery services. If your service is not listed, Custom SMTP may let you connect it with the host, port, username, and password supplied by that service. A built-in connection usually needs fewer choices because the guide is written for that service. Custom SMTP is useful when Mailrith does not have a built-in connection or when an organization uses its own mail relay. SMTP is not the same as a normal inbox login. A mailbox lets a person read email, while SMTP submits outgoing email. Some SMTP services require app passwords, IP allowlists, or specific sender permissions before SMTP sending works. The email delivery service often manages domain verification, custom DKIM, custom return-path, bounce handling, complaint handling, rate limits, and account reputation. Mailrith can use the connection, but Mailrith cannot make an unverified sender trustworthy by itself. For this reason, complete the email delivery service setup before you set up a campaign. If the email delivery service account cannot send from the chosen From email, or if DNS authentication is incomplete, the campaign editor cannot fix the delivery problem. 1. Choose the email delivery service that should send this type of email. 2. Verify the sender domain or sender address inside that email delivery service before creating a Mailrith campaign. 3. Prefer the built-in connection when Mailrith supports the email delivery service you use. 4. Use [Set Up Custom SMTP](https://mailrith.com/docs/setup-custom-smtp.md) only when your email delivery service or mail server supplies the required Custom SMTP details. 5. Confirm that your email delivery service signs email with your domain using [DKIM](https://mailrith.com/guides/dkim.md) and, where possible, uses a custom return-path for [SPF](https://mailrith.com/guides/spf.md). 6. Create the [Email Delivery Connection](https://mailrith.com/docs/email-delivery-connections.md) in Mailrith and assign it only to the correct workspaces. 7. Send a test email, then inspect the test email and delivery result before using the connection in a broadcast, sequence, or automation. 8. Set up email delivery service webhooks so [Bounces](https://mailrith.com/guides/bounces.md) and [Spam Complaints](https://mailrith.com/guides/spam-complaints.md) can update subscriber status in Mailrith. - Built-in service connections usually give Mailrith the clearest delivery updates. - SMTP sending requires the correct host, port, security mode, username, password, and allowed From email. - A successful SMTP login does not prove that SPF, DKIM, DMARC, or alignment are correct. - Email delivery service rate limits and account policies can still block or slow a send after Mailrith submits the message. - Use an email delivery service that shows bounces, complaints, suppressions, and rejected messages. - If you manage your own SMTP server, you are also responsible for TLS, PTR, queue health, abuse prevention, and IP reputation. > Mailrith controls the campaign. Your email delivery service controls the sending infrastructure. A healthy send requires both systems to be configured correctly. Related resources: - [Connect and Test an Email Delivery Connection](https://mailrith.com/guides/connect-and-test-provider.md): Use Mailrith's connection flow after the email delivery service account is ready. - [TLS and Secure Sending](https://mailrith.com/guides/tls.md): Understand secure email delivery service and SMTP connections. - [SMTP Errors, Deferrals, and Throttling](https://mailrith.com/guides/smtp-errors-deferrals-and-throttling.md): Understand what happens when an email delivery service or mailbox server slows or rejects mail. ## Related Guides - [Prepare the Sender Identity](https://mailrith.com/guides/prepare-sender-identity.md): Choose a sender name, sender email, reply-to address, and verified domain that match the trust you want subscribers to have in your email. - [Keep Permission and Compliance Simple](https://mailrith.com/guides/permission-and-compliance.md): Send to people who expect your email, identify yourself clearly, and make unsubscribing easy. - [Protect List Quality](https://mailrith.com/guides/protect-list-quality.md): A smaller list of people who want your emails is better than a large list of people who ignore or reject your emails.