Guide BillionMail Emails Stuck in the Send Queue: Read the Delay Reason and Fix It - Printable Version +- AdminsForum (https://adminsforum.com) +-- Forum: Free & open-source control panels (https://adminsforum.com/Forum-free-open-source-control-panels) +--- Forum: aaPanel (https://adminsforum.com/Forum-aapanel) +---- Forum: aaPanel Guides & Tutorials (https://adminsforum.com/Forum-aapanel-guides-tutorials) +----- Forum: aaPanel BillionMail Guides (https://adminsforum.com/Forum-aapanel-billionmail-guides) +----- Thread: Guide BillionMail Emails Stuck in the Send Queue: Read the Delay Reason and Fix It (/Thread-guide-billionmail-emails-stuck-in-the-send-queue-read-the-delay-reason-and-fix-it)

BillionMail Emails Stuck in the Send Queue: Read the Delay Reason and Fix It - JAY - 10-23-2026 BillionMail emails stuck in the send queue: read the delay reason and fix it When BillionMail can't deliver an email right away, it doesn't give up. It keeps the message in a queue and tries again later. A few messages there is normal. A queue that keeps growing means something is wrong, and the queue tells you exactly what, if you know how to read it. Where to find the queue Open Settings > Send Queue. At the top you'll find three buttons and a table: Refresh Queue reloads the list. Quick Clear deletes the queued messages. Use it only when you're sure you don't want them sent. Queue Parameter Configuration lets you adjust how the queue behaves. The defaults are fine for most people. The Delay Reason column is the important one. An empty list means everything was delivered. What the delay reasons mean "Connection timed out" (to port 25) Your server can't reach other mail servers. Almost always your VPS provider blocks port 25. See BillionMail not sending emails? How to check if port 25 is blocked. "Host or domain name not found" The recipient's domain doesn't exist or has no MX record. Usually a typo like Code:Copy gmial.com . Remove those addresses from your list. If it happens for every domain, your server's DNS resolver is broken: test with Code:Copy dig +short MX gmail.com . "421 ... try again later", "4.7.0 ... temporarily deferred", "rate limited" The receiving server (often Gmail, Outlook or Yahoo) is slowing you down. This happens with new IPs and sudden volume. It's a temporary error; BillionMail retries automatically. Send smaller batches, keep IP Warmup on in your tasks, and grow volume over a few weeks. "550 ... blocked", "listed at Spamhaus", "poor reputation" A permanent rejection. Your IP or domain is on a blacklist, or the receiver doesn't trust it. Check your IP on a blacklist checker, fix the cause, then follow the list's delisting steps. Retrying won't help until then. "550 5.7.x ... SPF / DKIM / DMARC / unauthenticated" Your authentication fails. Check Domain > DNS Records and our guide BillionMail DKIM fails even though the DNS record exists. "550 user unknown", "mailbox unavailable", "mailbox full" The address doesn't exist or can't receive mail. Remove it from your list; repeated bounces hurt your reputation. Working with the queue from the command line First, find your BillionMail folder and containers. Most commands below run from the BillionMail folder: aaPanel Docker install: Code:Copy /www/dk_project/dk_app/billionmail/billionmail_XXXX (the last part is random) Script install: usually Code:Copy /opt/BillionMail Code:Copy ls -d /www/dk_project/dk_app/billionmail/billionmail_* /opt/BillionMail 2>/dev/null docker ps --format "{{.Names}}" | grep -i billionmail The second command lists the containers, with names like Code:Copy billionmail_xxxx-postfix-billionmail-1 . Where a command says Code:Copy POSTFIX , Code:Copy DOVECOT or Code:Copy WEBMAIL , use your real container name. See the queue with full reasons: Code:Copy docker exec POSTFIX postqueue -p | tail -40 Retry everything now (after you fixed the cause): Code:Copy docker exec POSTFIX postqueue -f Delete one message (the ID is the first column of Code:Copy postqueue -p ): Code:Copy docker exec POSTFIX postsuper -d QUEUE_ID Delete all deferred messages at once (careful, there's no undo): Code:Copy docker exec POSTFIX postsuper -d ALL deferred Read the mail log for more detail. BillionMail keeps it in its folder: Code:Copy tail -n 100 logs/postfix/mail.log grep -i "status=deferred" logs/postfix/mail.log | tail -20 How long does BillionMail keep retrying? BillionMail uses Postfix for sending. By default Postfix keeps retrying deferred mail for up to 5 days, with growing gaps between tries, then returns it as undeliverable. So a message that sits in the queue for an hour isn't lost; it's waiting. Before you press Quick Clear Clearing the queue hides the symptom, not the cause. Read the delay reason, fix the problem, then retry with Code:Copy postqueue -f . Only clear messages you really don't want delivered, for example a campaign sent to the wrong group. Stuck? Post the delay reason (hide the recipient address) in this section. Sources: Postfix: postqueue · Postfix: postsuper · Postfix: maximal_queue_lifetime More BillionMail troubleshooting Port 25 blocked: emails not sending SSL certificate won't apply DKIM fails although the record exists Can't open the dashboard Webmail (Roundcube) problems Emails going to spam Update safely and roll back Applies to BillionMail 4.9 installed through aaPanel or the install script, October 2026.