Mass Email Sender

This Java-based application is for sending emails with an attachment to a large number of recipients at once. You can provide a list of emails as a CSV file, containing the receivers' names and email addresses. According to the details you provided an email will be sent to receivers. This program is containerized using Docker for ease of use in any environment.

This is how your output might look like if you are sending emails to request an internship. To customize this refer to the customization section.

Subject: Application for Software Engineering Internship at Google

Body:

Dear Sir/Madam,

I hope this message finds you well. My name is Sundar Pichai, and I am currently a third-year undergraduate studying 
Computer Science at the University of Colombo School of Computing. I am writing to express my keen interest in securing a 
Software Engineering internship position at Google.

...

I have attached my resume for your review and am available for an interview at your earliest convenience. Thank
you for considering my application. I look forward to the possibility of joining Google as a Software Engineering
intern and contributing to your team's success.

Best regards,
Buddhika Senanayake.
+94 71 234 5678
[email protected]
https://www.linkedin.com/in/buddhikanip/

Attachment: resume.pdf

Project Structure

.
├── Dockerfile
├── README.md
├── docker-compose.yml
├── pom.xml
└── src
    ├── main
    │   ├── java
    │   │   └── com
    │   │       └── email
    │   │           ├── EmailServer.java
    │   │           ├── Mail.java
    │   │           ├── Main.java
    │   │           └── User.java
    │   └── resources
    │       ├── Emails.csv
    │       ├── email_body.txt
    │       └── resume.pdf
    └── test
        └── java

Workflow

flowchart TD
    A[Start Application] --> B[Load Environment Variables]
    B -->|Success| C[Initialize Email Server]
    B -->|Failure| Z[Terminate Process]

    C --> D[Load Email CSV File]
    D -->|Success| E[Iterate Over CSV Rows]
    D -->|Failure| Z

    E -->|Valid Row| F[Extract Recipient Emails]
    E -->|Invalid Row| G[Log Invalid Row & Update Status]

    F -->|Recipients Found| H[Draft Email]
    F -->|No Recipients| I[Log Missing Recipients & Update Status]

    H --> H1[Set Email Subject]
    H1 --> H2[Generate Email Body]
    H2 --> H3[Attach Resume]

    H3 --> J[Send Email]
    J -->|Success| K[Log Success & Update Status]
    J -->|Failure| L[Log Failure & Update Status]

    E -->|Already Processed Row| M{More Rows?}
    M -->|Yes| E
    M -->|No| N[Write Results Back to CSV]

    N --> O[End Process]

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How to Run

Prerequisites

• Java 17 (or higher)
• Docker and Docker Compose (Optional)

Steps

1. Clone the Repository

   git clone https://github.com/Buddhikanip/Mass-Email-Sender.git
   cd Mass-Email-Sender

2. Set up your .env file

   • Copy the .env.example file to create your .env file:

     cp .env.example .env

   • Your newly created .env file looks like this.

      # Email server settings
      EMAIL_USERNAME=[email protected]
      EMAIL_PASSWORD=your-email-app-password
      EMAIL_HOST=smtp.gmail.com
      EMAIL_PORT=587
      
      # Email content
      EMAIL_SUBJECT=Application for Software Engineering Internship at {company}
      EMAIL_BODY=email_body.txt
      
      # Personal details for the cover letter
      NAME=Buddhika Senanayake
      PHONE=+94 71 234 5678
      EMAIL=[email protected]
      LINKEDIN=https://www.linkedin.com/in/buddhikanip/
      
      # Resume file
      RESUME=resume.pdf

     EMAIL_USERNAME: Your email address (send address)
     EMAIL_PASSWORD: If you are using Gmail this is a 16-digit passcode that allows a third-party app or device to access your Google Account. (Not your Gmail password) For reference

     If you are using some other email service your email server access password.

3. Update Emails.csv with your recipients details

4. Paste your own resume in src/main/resources directory and rename it as resume.pdf

5. Build and Run with Docker

   • Build and Run Docker image:

     docker-compose up --build

6. Run Without Docker

   • Compile the project:

     mvn clean install

   • Execute the application:

     java -jar target/<your-jar-file>.jar

7. Check Logs Monitor the logs to ensure emails are being sent:

   docker logs <container-id>

Key Files

• Emails.csv: Contains the recipient details and sending status.

• email_body.txt: A customizable template as text file containing email body.

  Dear Sir/Madam,
  
  I hope this message finds you well. My name is {name}, and I am currently a third-year undergraduate studying 
  Computer Science at the University of Colombo School of Computing. I am writing to express my keen interest in 
  securing a Software Engineering internship position at {company}.
  
  ...
  
  I have attached my resume for your review and am available for an interview at your earliest convenience. Thank
  you for considering my application. I look forward to the possibility of joining {company} as a Software Engineering
  intern and contributing to your team's success.
  
  Best regards,
  {name}.
  {phone}
  {email}
  {linkedIn}
  

• resume.pdf: Your resume file.

• .env.example: Example .env file.

Customization

• How to customize your recipient email list: Emails.csv

  Status	Company	Recipient 1	Recipient 2	Recipient 3
  Sent	Google	[email protected]	[email protected]	[email protected]
  Failed	Netflix	[email protected]	[email protected]
  Pending	Apple	[email protected]

  • First column: status

    Initially you can keep it empty. The program will append the status of the email to that column.

  • Second column: company name
  • Third column onwards

    Receiving emails under the specified company. One cell can contain only one email. If there's a second or third email for the same company, you can put them in the 4th column onwards

  Rows with the first column value as sent will be skipped without sending out the email. You can customize the logic in Main.java file (line 49-54).

  String status = row[0];
  if ("Sent".equalsIgnoreCase(status)) {
    log.info("Skipping already processed row: {}", Arrays.toString(row));
    updatedData.add(row);
    continue;
  }

• How to customize email subject

  Email subject is fetched from .env file (line 8). You can customize it according to your requirements. The {company} placeholder is replaced with the company name in Emails.csv. If you don't want the company name you can remove that placeholder. (This will work but is not recommended)

  EMAIL_SUBJECT=Application for Software Engineering Internship at {company}

  • Recommended way
    1. Remove {company} placeholder like above
    2. Update Mail.java draftEmail function first line as below

       String subject = user.emailSubject();

• How to customize email body: email_body.txt

  {comapny} in email_body.txt fetched from the second column of Emails.csv. {name} {phone} {email} {linkedIn} values are fetched from your .env file. In the email_body.txt place {company} {name} {phone} {email} {linkedIn} wherever you need to use their values. Then the values will be assigned to them by the below code snippet. (Mail.java line 45-49)

  String body = bodyTemplate.replace("{name}", user.name())
          .replace("{company}", company)
          .replace("{phone}", user.phone())
          .replace("{email}", user.email())
          .replace("{linkedIn}", user.linkedIn());

  If you don't want {name} {phone} {email} {linkedIn} as environment variables you can simply hardcode these values in your email_body.txt. Then you have to remove those variables form your .env , Main.java , User.java and Mail.java files.

  • If you want to remove them follow these steps.

    1. Remove below lines from .env. (line 11-15)

       # Personal details for the cover letter
       NAME=Buddhika Senanayake
       PHONE=+94 71 234 5678
       EMAIL=[email protected]
       LINKEDIN=https://www.linkedin.com/in/buddhikanip/

    2. Update Main.java line 34.

       User user = new User(emailSubject, emailBody, resume);

    3. Remove below lines from Main.java. (line 24-27)

       private static final String name = getEnv("NAME");
       private static final String phone = getEnv("PHONE");
       private static final String email = getEnv("EMAIL");
       private static final String linkedIn = getEnv("LINKEDIN");

    4. Update Mail.java line 45-49 as below.

       String body = bodyTemplate.replace("{company}", company);

    5. Update User.java line 3-5 as below.

       public record User(String emailSubject, String emailBody, String resume) {}

  Likewise, you can add new values to your email body.

• Send Email without Attachments

  1. Have to Update Mail.java file draftEmail function. Follow below steps.

     1. Remove this code section in draftEmail function.

        MimeBodyPart bodyPart = new MimeBodyPart();
        bodyPart.setText(body, "utf-8");
        
        MimeBodyPart attachmentPart = new MimeBodyPart();
        String attachmentPath = String.format("src/main/resources/%s", user.resume()); // Local path
        File resumeFile = new File(attachmentPath);
        if (!resumeFile.exists()) {
            attachmentPath = String.format("/app/resources/%s", user.resume()); // Docker path
        }
        attachmentPart.attachFile(attachmentPath);
        
        MimeMultipart multipart = new MimeMultipart();
        multipart.addBodyPart(bodyPart);
        multipart.addBodyPart(attachmentPart);
        mimeMessage.setContent(multipart);

     2. Paste this code line in deleted section.

        mimeMessage.setText(body, "utf-8");

     3. Final draftEmail function must look like this.

        public void draftEmail(String recipient, String company, User user) throws MessagingException, IOException {
           String subject = user.emailSubject().replace("{company}", company);
            
           // Read the cover letter
           String templatePath = String.format("src/main/resources/%s", user.emailBody()); // Local path
           if (!new File(templatePath).exists()) {
               templatePath = String.format("/app/resources/%s", user.emailBody()); // Docker path
           }
           String bodyTemplate = Files.readString(Paths.get(templatePath));
            
           // Replace placeholders with actual values
           String body = bodyTemplate.replace("{name}", user.name())
               .replace("{company}", company)
               .replace("{phone}", user.phone())
               .replace("{email}", user.email())
               .replace("{linkedIn}", user.linkedIn());
            
           mimeMessage = new MimeMessage(newSession);
           mimeMessage.addRecipient(Message.RecipientType.TO, new InternetAddress(recipient));
           mimeMessage.setSubject(subject);
           mimeMessage.setText(body, "utf-8");
        }

  2. Remove below line in .env file.

     # Resume file
     RESUME=resume.pdf

  3. Update Main.java file as below.

     1. Remove below code line.

        private static final String resume = getEnv("RESUME");

     2. Update below code line. (Remove resume in the constructor)

        User user = new User(name, phone, email, linkedIn, emailSubject, emailBody);

  4. Update User.java file. (Remove String resume in the constructor)

     public record User(String name, String phone, String email, String linkedIn, String emailSubject, String emailBody) {}

• Send multiple attachments

  1. Update Mail.java file draftEmail function file attachment section as below.

     These example file names are hardcoded in an array list. If you want to get them via .env you can add these file names as an array and fetch them in Main.java and so on.

     List<String> attachments = Arrays.asList("resume.pdf","portfolio.pdf");
     
     MimeMultipart multipart = new MimeMultipart();
     multipart.addBodyPart(bodyPart);
     
     for (String attachment : attachments) {
         MimeBodyPart attachmentPart = new MimeBodyPart();
         String attachmentPath = String.format("src/main/resources/%s", attachment); // Local path
     
         File file = new File(attachmentPath);
         if (!file.exists()) {
              attachmentPath = String.format("/app/resources/%s", attachment); // Docker path
         }
         attachmentPart.attachFile(attachmentPath);
         multipart.addBodyPart(attachmentPart);  
     }
     
     mimeMessage.setContent(multipart);

Features

• File Attachment: Automatically attach the specified file.
• Dockerized Deployment: Simplifies setup and ensures a consistent environment.
• Multiple Emails At Once: Sends specified emails to a large number of specified receivers at once.
• Customizable: Output can be customized according to your own will.
• CSV-based Management: Tracks sending status and recipient details.

License

This project is licensed under the MIT License - see the LICENSE file for details.

Contributions

Feel free to submit issues or pull requests for improvements