Maintaining a consistent email sending volume with Shopify Messaging

Maintaining a consistent email sending volume helps build trust with email providers so that your campaigns successfully reach customers' inboxes. Providers such as Gmail, Yahoo, and Outlook monitor sending patterns and might defer, throttle, or block messages when they detect sudden spikes. This means that even if sends succeed on your end, subscribers might receive messages late or not at all.

This page covers strategies for maintaining consistent volume, increasing capacity safely, and recovering from delivery issues. If you're new to Shopify Messaging, then building your sender reputation and sending warm-up emails are especially important.

Practices that can trigger email blocks or delays

The following practices can cause providers to block or delay messages until they verify that you're a legitimate sender:

• Sending 5 times your normal email volume in a single day.
• Long gaps in sending followed by large email campaigns.
• Sudden spikes in sending without gradual increases.
• Poor list quality, such as buying or scraping lists. To learn more, refer to Maintaining a high quality subscriber list.

Diagnosing email delivery issues

Volume spikes are the most common cause of blocks and delays from email providers. Providers monitor your sending patterns and take action when you send too much too quickly. When you send significantly more than your usual pattern, they might defer messages, throttle delivery (accept mail at a slower rate), route more messages to spam or promotions folders, or temporarily block sends.

If you notice any of the following signs, then volume spikes might be impacting your deliverability:

• Emails to Gmail, Yahoo, or Outlook are delayed by hours or days
• Sudden drop in open rates for specific email providers
• Subscribers reporting that they didn't receive your email campaign
• Increased spam folder placement

For example, if you typically send 2,000 emails per day and suddenly send 10,000 in one hour, then providers might deliver the first batch and defer or throttle the rest, so some messages arrive hours or days later, or don't deliver.

Tips for avoiding blocks and delays

Review the following best practices for maintaining volume consistency and avoiding blocks and delays:

• Monitor your spam complaint rate and keep it low to avoid blocks.
• Maintain a consistent sending schedule with the following best practices:
  • Send emails on a regular schedule, such as daily, weekly, or bi-weekly.
  • Keep your volumes similar from day-to-day and week-to-week.
  • Avoid long gaps between email campaigns followed by large sends.
• Focus on engaged subscribers first (for example, those who opened or clicked recently). For list quality and segmentation tips, refer to Maintaining a high quality subscriber list.
• When you need to increase volume, do it gradually. To learn more, refer to Increase your email volume gradually.

Increasing your email volume gradually

If you need to increase your email volume to send to more subscribers, then do so gradually using the following guidelines:

• Increase your send volume by 20-30% each week until you reach your target volume. Avoid increasing by more than 30% per week, even if you have an established sender reputation. To learn more about safe increases, refer to Gmail's email sender guidelines (the same principle applies to other providers).
• Monitor your delivery metrics, such as open rates, click rates, and spam complaints as you increase volume.
• Continue increasing volume each week until you reach your target.

For example, if you currently send 5,000 emails per week and want to reach 15,000, then plan for a 6-week ramp-up:

Handling large or infrequent campaigns

When a campaign is larger than your usual volume or you send only one time per month, spread sending across multiple days or throughout the day so that email providers don't treat it as a volume spike and delay or block delivery.

Approaches to sending your large campaign consistently

Consider any of the following approaches when sending a large campaign to prevent volume spikes:

• Same volume each day: Send a consistent number per day so email providers recognize your volume as normal. For example, 5,000 emails per day over 4 days instead of 20,000 in one day, or 5,000-7,000 per day over 3-4 days.
• Smaller batches at set times: Send to portions of your list at different times across one or two days. For example, 25% in the morning, 25% in the afternoon, 25% the next morning, and 25% the next afternoon. This keeps hourly send rates manageable.
• Micro-batching at regular intervals: Send smaller batches at regular intervals throughout the day. For example, 2,500 emails every 2 hours instead of 20,000 in one send (eight sends over 16 hours, 1-2 days). This helps email providers recognize a consistent hourly pattern.

Any of these approaches reach your full audience and help prevent blocks.

Monthly sending best practices

If you send only one time per month, then apply one of the following approaches that work well for a monthly cadence:

• Same-day segmentation: Send to 25% of your subscriber list every 6 hours throughout the day.
• Multi-day approach: Send to 50% of your list on Day 1 and the remaining 50% on Day 2.
• Extended timeline: Divide your list into 3-4 segments and send one segment per day over 3-4 days.

Preparing for seasonal campaigns

Plan ahead for seasonal events such as Black Friday, Cyber Monday, holiday sales, and other events that require you to email more subscribers than usual. Start increasing your volume 4-6 weeks before your campaign to establish the new pattern.

For example, if you normally send 5,000 emails per week but need to send 15,000 for a seasonal campaign, then increase your send volume as follows:

• 6 weeks before: Start at your current baseline of 5,000 emails 6 weeks ahead of time.
• Weeks 1-5: Increase your send volume by 20-30% each week.
• Campaign week: Send at your target volume of 15,000.

This gradual approach gives email providers time to recognize the increase as legitimate growth.

Recovering from blocks and delays

If your emails are being blocked or delayed after a volume spike, then take the following steps to restore your sender reputation:

• Reduce your send volume to your previous baseline or lower.
• Send only to your most engaged subscribers (for example, those who opened or clicked in the last 30 days). To learn more about targeting engaged subscribers, refer to Maintaining a high quality subscriber list and Customer segments.
• Maintain consistent sending for several weeks to rebuild trust with email providers.
• Gradually increase volume using the 20-30% weekly increase when your metrics stabilize.

Recovery typically takes several weeks. You'll know that your delivery is improving when emails reach inboxes within minutes, open rates return to normal, you experience fewer deferrals or "try again later" responses, and subscribers report receiving your campaigns.