Duplicate emails can occur in an SMTP Python setup for several reasons. Some of the common causes are:
Incorrect email address: If the email address is incorrect or misspelled, the email will be sent to the wrong recipient. This can result in duplicates being sent to multiple recipients.
Mail server misconfiguration: The mail server might be configured in a way that causes it to send multiple copies of the same email.
Multiple calls to the sendmail function: If the same email is sent multiple times by calling the sendmail function multiple times, this can result in duplicates being sent.
Use of CC and BCC fields: When using the CC (carbon copy) and BCC (blind carbon copy) fields, it's possible to send the same email to multiple recipients. This can result in duplicates being sent if the same recipient is included in both the CC and BCC fields.
To avoid duplicate emails, it's important to ensure that the email address is correct, the mail server is properly configured, and the sendmail function is only called once per email. Additionally, it's important to carefully use the CC and BCC fields to avoid sending duplicates.
In some cases, it might also be necessary to implement additional logic to check for duplicates before sending an email. For example, you could maintain a database of previously sent emails and check against it before sending each new email.
To avoid sending duplicate emails, you can add a unique identifier to each email message, such as a message ID or a hash of the message content, and keep track of the emails you have sent in a database. Before sending an email, you can check the database to see if the message has already been sent. If it has, you can avoid sending the duplicate email. Additionally, you can add a check to make sure that the email was successfully delivered, and update the database accordingly. This will prevent you from sending the same email multiple times in the event of a delivery failure. To implement these checks in Python, you can use a library such as SQLite or PostgreSQL to store the email information and track the status of each email message.