如何用RCurl/Curl包在R中通过SMTP协议发送邮件？

Absolutely! You can skip mailR and its RJava dependency entirely—both RCurl and the modern curl package let you send emails directly over SMTP. Here are step-by-step examples for both tools:

Option 1: Using RCurl #

RCurl leans on libcurl under the hood, so it fully supports SMTP with authentication and encryption. Start by defining your email and server settings:

library(RCurl)

# Configure core email/SMTP details
smtp_server <- "smtp.office365.com"  # Example for Outlook/Office 365
smtp_port <- 587
username <- "your-email@example.com"
password <- "your-password-or-app-specific-password"
from <- "your-email@example.com"
to <- "recipient@example.com"
subject <- "Test Email from RCurl"
body <- "Hello! This is a test email sent using RCurl via SMTP."

# Build the full email content (including required headers)
email_content <- paste0(
  "From: ", from, "\n",
  "To: ", to, "\n",
  "Subject: ", subject, "\n\n",
  body
)

# Send the email
curlPerform(
  url = paste0("smtp://", smtp_server, ":", smtp_port),
  mail.from = from,
  mail.rcpt = to,
  upload = TRUE,
  infile = textConnection(email_content),
  smtp.username = username,
  smtp.password = password,
  ssl.verifypeer = TRUE,  # Keep this enabled for security unless troubleshooting
  ssl.verifyhost = TRUE,
  verbose = TRUE  # Optional: adds debug logs to help diagnose issues
)

Quick RCurl Notes: #

• For Gmail, use smtp.gmail.com on port 587, and you’ll need an app-specific password if two-factor authentication is turned on.
• If you hit SSL errors, temporarily set ssl.verifypeer = FALSE (but only for testing—this reduces security).

Option 2: Using the curl Package (Modern Alternative) #

The curl package is a more intuitive wrapper around libcurl, with a dedicated helper for sending emails:

library(curl)

# Define email content
email_details <- list(
  from = "your-email@example.com",
  to = "recipient@example.com",
  subject = "Test Email from curl Package",
  body = "Hi there! This email was sent using the curl package in R."
)

# Define SMTP server settings
smtp_settings <- list(
  server = "smtp.gmail.com",
  port = 587,
  username = "your-email@gmail.com",
  password = "your-app-specific-password",
  use_ssl = "starttls"  # Use "ssl" for port 465, "starttls" for 587 (most common)
)

# Send the email
curl_send_mail(
  from = email_details$from,
  to = email_details$to,
  subject = email_details$subject,
  body = email_details$body,
  smtp_server = smtp_settings$server,
  smtp_port = smtp_settings$port,
  smtp_user = smtp_settings$username,
  smtp_password = smtp_settings$password,
  use_ssl = smtp_settings$use_ssl
)

Quick curl Package Notes: #

• For HTML emails, pass a formatted HTML string as body and add content_type = "text/html" to the curl_send_mail() call.
• This package handles SSL setup more smoothly than RCurl for most providers.

General Best Practices #

• Always check your email provider’s official SMTP docs for the correct server address, port, and authentication rules.
• Never hardcode passwords in your script—use environment variables like Sys.getenv("EMAIL_PASSWORD") instead for security.
• If authentication fails, verify if your provider requires enabling "less secure apps" (being phased out by most) or using an app-specific password.

内容的提问来源于stack exchange，提问作者Jan