How to retry failed send swiftmailer mails

SwiftMailer is a popular PHP library for sending emails. If you're using SwiftMailer in a Swift-based project (e.g., SwiftUI, SwiftNIO), you can retry failed send operations using various approaches. Here are a few ways to retry failed send emails with SwiftMailer:

Using a retry mechanism in SwiftMailer: SwiftMailer provides a built-in retry mechanism through its setRetryLimit and setRetryDelay methods. You can set the number of retries and the delay between retries using these methods.

Example:

import SwiftMailer

let mailer = SwiftMailer()
mailer.setRetryLimit(3) // retry up to 3 times
mailer.setRetryDelay(300) // delay 5 minutes between retries

Implementing a custom retry mechanism: You can create a custom retry mechanism by wrapping the email sending logic in a loop that retries the send operation until it succeeds or reaches a maximum number of retries.

Example:

import SwiftMailer

func sendEmail() {
    var retries = 0
    while retries < 3 {
        do {
            try mailer.sendEmail()
            break
        } catch {
            retries += 1
            print("Email failed to send. Retrying in 5 minutes...")
            usleep(3000000000) // 5 minutes in microseconds
        }
    }
}

Using a third-party library: There are several third-party libraries available that provide retry mechanisms for SwiftMailer, such as swiftmailer-retry or swiftmailer-resilience. These libraries can simplify the process of implementing retries and provide more advanced features.

Example (using swiftmailer-retry):

import SwiftMailer
import SwiftmailerRetry

let mailer = SwiftMailer()
let retryPolicy = RetryPolicy(retries: 3, delay: 300)
mailer.setRetryPolicy(retryPolicy)

Using a queueing system: If you're using a queueing system like RabbitMQ, Apache Kafka, or Amazon SQS, you can send emails to a queue and have the queueing system retry failed sends automatically. This approach decouples the email sending logic from your application and provides a more scalable and fault-tolerant solution.

Remember to adjust the retry mechanism according to your specific use case and requirements. You may want to consider factors like the maximum number of retries, delay between retries, and the error handling strategy.

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How to retry failed send swiftmailer mails