Close uses your existing email account's SMTP server to send mail. That works well for normal email volumes but hits a ceiling when you want to send bulk email — outbound cadences, sequences, or any mailing to large segments of your lead base.
Why standard email accounts hit a wall
Every email server has a daily send-rate limit. Gmail, Google Workspace, Microsoft 365, and other provider accounts cap how many messages you can send per day to prevent abuse. Once you hit that ceiling, your mail server stops sending — not just from Close, but from every app connected to that account.
For typical limits, see Email sending limits.
Limits
Although Mailgun, SendGrid, and others are better suited for bulk email sending than Gmail, it doesn't mean they offer unlimited email sending. They also have limits in place to prevent spam/abuse. Read more on Mailgun's probation period.
When registering with any such service, please make sure you know your hourly/daily sending limits to avoid being disconnected from Close.
Mailgun, SendGrid, and other 3rd party email services are usually used for sending out Workflows and Bulk emails.
What a dedicated email service gives you
A dedicated email service (sometimes called an ESP or email service provider) lets you send at volumes well above what a personal mailbox or business email account allows. You connect it to Close via SMTP, and Close uses the dedicated service for outbound delivery while your existing inbox continues handling replies.
Two providers have detailed setup guides in this catalog:
Close supports any SMTP-compatible bulk email service. If you're using a different provider, the connection works the same way - configure their SMTP credentials in Close's Custom Email setup rather than following a provider-specific walkthrough.
Service limits still apply
Mailgun, SendGrid, and other dedicated services have their own sending limits to prevent spam and abuse. Limits vary by plan; check your provider's documentation before scaling sending volume. New accounts typically have a warm-up or probation period during which limits are stricter.
Compliance requirements
Sending bulk email through any service — Close, Mailgun, SendGrid, or another — means meeting the deliverability requirements that major mailbox providers enforce. See Requirements for bulk email senders for the full list: SPF, DKIM, DMARC, TLS, PTR records, one-click unsubscribe, and spam-rate thresholds. Using a dedicated email service doesn't exempt you from these requirements.
For general deliverability practices including sender warm-up and reputation monitoring, see Email deliverability.
Modifying DNS records
Setting up a dedicated email service requires changes to your domain's DNS records. Incorrect DNS changes can prevent your organization from sending or receiving any email, take your website offline, or break other services that depend on DNS. Have your IT provider or whoever manages your domain make these changes if you're not familiar with DNS administration.
Domain host credentials
You'll need administrative access to your domain host (the company you registered your domain with) to make DNS changes. Common domain hosts include GoDaddy, Namecheap, Network Solutions, Rackspace, Digital Ocean, and Cloudflare. If you're not sure who hosts your domain, look up your domain on ICANN Lookup and check the registrar field.
Provider setup
Follow the walkthrough for your chosen provider:
For any other SMTP-compatible service, use the provider's SMTP credentials in Close's Custom Email setup.