Signal & Syntax · Email deliverability
What Is SMTP?
SMTP (Simple Mail Transfer Protocol) is how mail servers send email to each other. RFC 5321 defines SMTP.SMTP (Simple Mail Transfer Protocol) is how mail servers send email to each other. RFC 5321 defines SMTP.SMTP (Simple Mail Transfer Protocol) is how mail servers send email to each other. RFC 5321 defines SMTP.
Also calledSimple Mail Transfer Protocol
Example
RCPT TO:<sofia.marin@acmecorp.com> 250 2.1.5 OK
SMTP in Practice
A sending server connects to the recipient's MX host and opens an SMTP conversation. The receiving server answers each command with a three-digit status code. RCPT TO is the command naming the mailbox. The reply to RCPT TO carries the verdict a verification check reads.A sending server connects to the recipient's MX host and opens an SMTP conversation. The receiving server answers each command with a three-digit status code. RCPT TO is the command naming the mailbox. The reply to RCPT TO carries the verdict a verification check reads.A sending server connects to the recipient's MX host and opens an SMTP conversation. The receiving server answers each command with a three-digit status code. RCPT TO is the command naming the mailbox. The reply to RCPT TO carries the verdict a verification check reads.
Where ScoreMachine Fits
Related Terms
Read the Guide
Guide
MX Records, SMTP Codes and Bounces Explained
How an email finds a mailbox, and how the server answers. Read the guide →Run the Checks on Your Own List
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