Fluent SMPT Send Time Optimazation

  • Resolved buddharide

    (@buddharide)


    11 months, 3 weeks ago

    I’d like to integrate Mailgun’s Send Time Optimization (STO) into our FluentSMTP workflow. STO improves email engagement by delivering messages exactly when subscribers are most active. (Mailgun docs here). The technical bit:

    STO activates through a simple SMTP header: X-Mailgun-Delivery-Time-Optimize-Period: 24h

    We could insert this easily via FluentSMTP’s hook:

    add_filter('fluentsmtp_mailer_custom_headers', function($headers, $phpmailer) { $headers['X-Mailgun-Delivery-Time-Optimize-Period'] = '24h'; return $headers; }, 10, 2);

    Key Question:

    Where should we place the toggle for turning STO on or off?

    • Option A (Connection-level):
      Toggle lives in FluentSMTP’s Mailgun connection settings. Clean, centralized, applies broadly.
      Pros: Simple, consistent.
      Cons: Less flexibility per-campaign.
    • Option B (Campaign-level):
      Toggle lives in FluentCRM campaign settings.
      Pros: Granular control per campaign.
      Cons: Potential UX clutter, more complexity.

    I lean toward Option A (Connection-level) because it’s clean, intuitive, and likely easier for users to manage. But I want your take:

    • What makes the most sense from your perspective?
    • Is there anything technically we should consider before moving forward?

    Thanks!

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  • Plugin Support Md. Ashikur Rahman – WPManageNinja

    (@ashiik)

    11 months, 3 weeks ago

    Hello @buddharide!

    I hope you are doing great today! Thank you for your detailed suggestion and for exploring ways to enhance email deliverability through Mailgun’s Send Time Optimization (STO) feature—great initiative!

    The specific hook you mentioned (fluentsmtp_mailer_custom_headers) is not available in FluentSMTP, so inserting the custom Mailgun header directly through FluentSMTP is not supported.

    FluentCRM does offer a filter that may be helpful if you’re sending emails through FluentCRM and want to add custom email (MIME) headers:

    add_filter('fluent_crm/email_headers', function($headers, $data) {
    $headers[] = 'X-Mailgun-Delivery-Time-Optimize-Period: 24h';
    return $headers;
    }, 10, 2);

    You will find more details here: FluentCRM Developer Doc. If you find the expected output using via this process, we would be happy hear that.

    As for adding a UI toggle at the connection or campaign level for STO, it’s a valuable suggestion. However, since the whole STO flow with Mailgun hasn’t been fully tested on our side, I can’t yet recommend which placement (connection-level or campaign-level) would be best without further internal analysis.

    I’d be happy to forward this idea to our R&D team as a feature request. They’ll assess feasibility and determine the most suitable implementation path. Please note that while we welcome feature requests, we can’t provide a specific ETA.

    Let me know if you’d like me to pass this along to the team. You may also let me know here.

    Thank you for staying with FluentCRM!

Viewing 1 replies (of 1 total)

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