SMTP Mailer is a streamlined email sending service designed for AI agents and automation workflows to deliver messages through any standard SMTP server. It accepts connection credentials via an intuitive URL format supporting both plain SMTP and encrypted SMTPS connections, making configuration straightforward without complex parameter handling. Recipients can be specified as a single address, an array, or a comma-separated string, with support for CC and BCC fields for flexible distribution. The tool sends both plain text and HTML formatted emails, enabling rich content delivery including formatted newsletters, styled notifications, and branded communications. File attachments are supported through base64-encoded content with configurable MIME types for documents, images, and other media. Email priority levels allow marking messages as low, normal, or high importance for recipient mail client handling. The sender address can be explicitly set or automatically derived from the SMTP username, simplifying configuration for common use cases. This tool is optimized specifically for email delivery. For workflows requiring additional protocols such as FTP file transfers, SSH command execution, or MQTT messaging alongside email, use the Protocol Bridge tool which provides a unified interface across multiple network protocols.
Description:Use 'get_instructions' to retrieve documentation. Action to perform: send
Default:send
Allowed values:
get_instructionssend
smtp_url
Type:string
Description:SMTP server URL containing host, port, and credentials. The URL scheme determines security:
• smtp:// - STARTTLS on port 587 (recommended)
• smtps:// - SSL/TLS on port 465
Format: smtp://username:password@hostname:port
Examples:
• Gmail: smtp://your.email@gmail.com:app-password@smtp.gmail.com:587
• Outlook: smtp://your.email@outlook.com:password@smtp-mail.outlook.com:587
• Custom: smtp://user:pass@mail.example.com:587
Note: Gmail requires App Password (not regular password). Generate at: https://myaccount.google.com/apppasswords
to
Type:array
Description:Recipient email address(es). Required field. Can be:
• Array of strings: ["user1@example.com", "user2@example.com"]
• Single string: "user@example.com"
• Comma-separated: "user1@example.com,user2@example.com"
At least one recipient is required.
Array items:string
subject
Type:string
Description:Email subject line. Required field. Keep concise and descriptive.
Examples:
• "Monthly Report - January 2025"
• "Password Reset Request"
• "Welcome to Our Platform!"
body
Type:string
Description:Email body content. Required field. Can be plain text or HTML depending on body_type.
Plain text example:
"Hello,\n\nThank you for signing up!\n\nBest regards,\nThe Team"
HTML example:
"<html><body><h1>Welcome!</h1><p>Thank you for <strong>signing up</strong>.</p></body></html>"
from_email
Type:string
Description:Sender email address. Optional - defaults to username from smtp_url.
Useful when:
• Authenticating with one account but sending from another
• Using service accounts (e.g., smtp://auth@example.com but from noreply@example.com)
Note: Some providers (like Gmail) enforce that from_email matches your account.
Example: "noreply@company.com"
body_type
Type:string
Description:Email body format. Determines how the body content is interpreted.
• 'plain' - Plain text (default). Line breaks preserved, no formatting.
• 'html' - HTML content. Supports formatting, images, links, etc.
Default: plain
Default:plain
Allowed values:
plainhtml
cc
Type:array
Description:CC (Carbon Copy) recipients. Optional. Visible to all recipients.
Array of email addresses: ["manager@example.com", "team@example.com"]
Recipients in CC receive the email and can see who else received it.
Array items:string
bcc
Type:array
Description:BCC (Blind Carbon Copy) recipients. Optional. Hidden from other recipients.
Array of email addresses: ["archive@example.com", "audit@example.com"]
Recipients in BCC receive the email but are not visible to other recipients. Useful for:
• Archive/audit trails
• Private notifications
• Mass emails where recipients shouldn't see each other
Array items:string
attachments
Type:array
Description:Email attachments. Optional. Maximum total size: 25MB.
Each attachment is an object with:
• filename (string, required): File name with extension (e.g., "report.pdf")
• content (string, required): Base64-encoded file content
• content_type (string, optional): MIME type (e.g., "application/pdf"). Default: "application/octet-stream"
Example:
[
{
"filename": "report.pdf",
"content": "JVBERi0xLjQKJeLjz9MK...",
"content_type": "application/pdf"
},
{
"filename": "data.csv",
"content": "TmFtZSxBZ2UsQ2l0eQ0K...",
"content_type": "text/csv"
}
]
Common MIME types:
• PDF: application/pdf
• CSV: text/csv
• Excel: application/vnd.openxmlformats-officedocument.spreadsheetml.sheet
• Images: image/png, image/jpeg
• Text: text/plain
Array items:object
priority
Type:string
Description:Email priority/importance level. Sets the X-Priority header.
• 'low' - Low priority (X-Priority: 5)
• 'normal' - Normal priority (X-Priority: 3, default)
• 'high' - High priority (X-Priority: 1)
High priority emails may be marked with a red exclamation in email clients. Use sparingly to avoid being treated as spam.
Default: normal
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About The Developer
Apoth3osis
★13 stars
Joined Agent Payment: August 14, 2025
We build tools that enable AI agents to excel in the mathematical realm.
Our small team develops experimental and unique solutions in the AI arena, with a strong focus on modular computing for agentic applications and custom model deployment. We have handled projects for a variety of applications across many sectors, from algorithmic trading and financial analysis, to molecular simulations and predictions, to habitat and biodiversity monitoring and wildlife conservation.
