How does Unify prioritize sending emails in the queue?

Last updated: May 4, 2026

Email Prioritization in Sequences:

Emails in sequences are handled based on simple queue principles. Here’s how the system prioritizes sequence emails:

  1. All sequence emails are assigned a default LOW priority.

  2. After being assigned a low priority, emails are sent in the order they were added to the queue. This process works on a FIFO (First-In, First-Out) basis. The next email in a sequence is added to the queue only after the previous one has completed.

  3. There is no inherent priority difference between Step 1, Step 2, or Step 3 emails within a sequence. The order of dispatch is entirely dependent on the time they were added to the queue.

  4. The "urgent" priority tag applies only to manual emails in BDR tasks, not to automated sequence emails. All sequence emails maintain LOW priority regardless of any urgency settings.

Additional Context:

Unify does not give special prioritization to emails further along in the sequence (e.g., Steps 2 and 3) as compared to new enrollments (Step 1). Similarly, new enrollments are not prioritized over existing sequences. The system ensures fairness by processing all emails in the strict order they entered the queue, provided they share the same priority level.

Current Limitations and Workarounds:

While Unify currently does not support prioritizing specific sequences over others, there are several workarounds for urgent campaigns:

  • Pause competing sequences: Temporarily pause other sequences that share the same mailbox to give your urgent sequence full access to the sending capacity.

  • Dedicate a mailbox: Assign a specific email address exclusively to high‑priority sequences and remove all other senders from that mailbox. This ensures your priority emails won’t compete with other sequences in the queue.

  • Add more mailboxes: Increase send capacity for your urgent sequence by adding additional mailboxes to its mailbox group.

  • Reassign queued enrollments to mailboxes with lower backlogs: Use the Email Backlog > Reassign Sequence Enrollments feature to move Step 1 "queued" enrollments to mailboxes that have smaller backlogs. Note: This only works for enrollments that are in Step 1 and in "queued" status.

Daily Send Limits Impact on Email Queue Scheduling

Daily send limits per mailbox affect scheduling. Each mailbox has a daily send limit of 25 emails. Once this limit is reached, additional emails in the queue will be scheduled for the next available sending slot (typically the following day), even if they were added to the queue with minimal delay settings in the sequence.

Email Delay Calculation in Sequences

While the published article explains how emails are prioritized once in the queue, there's an important detail about when emails enter the queue that affects timing:

Delay Timing Mechanics: Delays between sequence steps are counted in calendar days (including weekends), but emails only send on business days.

Send schedule windows affect queue timing. Even if a sequence has no initial delay, emails will only be queued for sending during your configured send schedule window. If you enroll a contact outside of your send window (e.g., after 4 PM when your schedule ends at 4 PM), the email will be queued for the next available time within your send window, typically the following morning.

  • If Email 1 sends on Friday morning and Email 2 has a 1‑day delay, Email 2 is “due” on Saturday but will be queued for Monday morning within your send window.

  • The delay calculation starts immediately after the previous email sends, regardless of whether the “due date” falls on a weekend.

  • Emails that become “due” on weekends are automatically queued for the next business day.

  • Delays are calculated from task completion, not due date. If a previous sequence step (such as a phone call task) was due on one date but completed later, the delay timer starts from the completion date. For example, if a call task was due March 19 but completed April 7, and the next email has a 2‑day delay, that email will be queued for April 9, not March 21.

This timing mechanism determines when emails enter the FIFO queue system, which then processes them in order of arrival as described in the main prioritization article.

Sequence Overlap Prevention and Conflict Management

Sequence Enrollment Conflicts: Unify automatically prevents contacts from being enrolled in multiple sequences simultaneously. When multiple sequences target the same contacts, the system uses a first‑come, first‑served approach – the sequence launched first takes priority, and the contact will not be enrolled in subsequent sequences until the first sequence is completed.

Managing Sequence Conflicts: If you need to prioritize a new sequence over an existing one targeting the same contacts, you’ll need to manually intervene since the automatic prevention system favors the first sequence. The solution is to pause the existing sequence first – navigate to the sequences page, click into the sequence, and toggle it to “Paused”. This allows the new sequence to enroll those contacts.

This means that even though emails enter the queue immediately after enrollment and follow FIFO ordering, users may see their emails scheduled for future dates when the daily send capacity has been exhausted. This is a normal part of the system's operation and helps maintain proper sending limits for deliverability.

How to Implement the Dedicated Mailbox Workaround for Priority Sequences

Important Clarification: Mailbox routing can only be configured in Play Builder through the Sequence node, not directly in the sequence interface itself.

  1. Configure sequence routing: In Play Builder, open the Sequence action for your priority campaign and click Edit persona routing.

  2. Assign dedicated mailboxes: Add only your dedicated mailboxes to this sequence's routing.

  3. Remove mailboxes from other sequences: Remove those mailboxes from routing in any other sequences to make them exclusive to this campaign.

  4. Save and republish: Save your changes and republish the play so the routing updates take effect.

Tip: Finalize mailbox assignments before queuing any manual emails to avoid re‑enrollment of steps. This prevents disruption to your sequence flow and ensures clean implementation.

For additional details on mailbox setup, see How to set up additional mailboxes in a sequence.

Note that the ability to prioritize specific sequences is planned for future development.

Monitoring and Managing Email Queue Capacity

Email Delivery Timing Details

Emails are intentionally staggered by approximately 2‑4 minutes between sends to protect deliverability. This staggering occurs within the FIFO queue processing and helps maintain good sender reputation.

Monitoring Email Backlog and Capacity

Check mailbox capacity: Navigate to Dashboard → Health → Email Backlog to identify which mailboxes have remaining daily send capacity. This view shows you which mailboxes are backlogged versus those with available capacity.

Reassign to optimize delivery: If a mailbox is backlogged, reassign the sequence enrollment to a mailbox with lower backlog to move emails into a queue with fewer pending sends. This can significantly improve delivery timing for urgent campaigns.

Checking Scheduled Send Times

You can check the scheduled send time for any queued email by clicking into the specific email to see when it will be sent based on current mailbox capacity and queue order. This visibility helps you understand exactly when your emails will be delivered and whether capacity adjustments are needed.