SMTP (Simple Mail Transfer Protocol) is the internet standard for sending email. An SMTP server is the service that takes your outgoing email and delivers it to the recipient's mail server, a bit like a post office sorting and dispatching letters.
Why it matters
Every email campaign, receipt and newsletter goes out through an SMTP server. Which server you use, and how it's set up, affects:
- Deliverability: authenticated, reputable servers land in the inbox more often
- Sending limits: each provider caps volume
- Separation: using different servers for marketing and transactional mail protects critical emails
Setting up SMTP well
- Send from your own domain
- Publish SPF, DKIM and DMARC records
- Warm up new servers gradually
- Monitor bounces and complaints
Unlimited SMTP on RapBooster
RapBooster Email lets you connect unlimited SMTP servers in one dashboard, on a plan per connected mailbox (see pricing). Each SMTP provider's own limits still apply.
Example
An agency connects three SMTP servers, one per client brand, so each brand's reputation stays separate while the team manages everything from one account.
Related terms
SPF · DKIM · DMARC · Email deliverability
Guide: what is unlimited SMTP?
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