What you’re seeing
- Some messages to outside addresses arrive normally while others sit in the queue for hours.
- Queued messages show retry errors about being unable to connect or having no route.
- Senders eventually receive a delayed delivery notice, but Outlook showed no error at the time.
- The pattern began the week older Exchange servers were powered off.
Common causes
Every environment is different, but these are the causes our engineers find most often:
- A send connector still lists a retired server as one of its source servers, so part of the outbound traffic is routed to a machine that no longer exists.
- The old servers are still registered in Active Directory, so Exchange routing continues to consider them as valid hops.
- A smart host, relay service or spam filter only accepts mail from the old server's IP address.
- The firewall allows outbound SMTP only from the retired server's address.
- Your SPF record lists the old server's IP address but not the new one, so some recipients defer or reject the mail.
Why it matters
Intermittent mail problems are harder on a business than outright outages, because nobody knows which messages made it. Quotes, contracts and time-sensitive replies may arrive hours late or not at all, and customers conclude that you are slow to respond. Staff start resending messages and copying in personal accounts to be safe, creating confusion and a compliance headache. The longer the cause goes unidentified, the more lost correspondence builds up that someone will eventually have to chase.
How AskTechGurus fixes it
Skip the trial and error. A certified engineer works on your actual system, finds the root cause, and fixes it properly.
Tell us what’s happening
Submit a ticket in about two minutes. Paste the error, describe what changed, and pick your tier. No charge to submit.
A certified engineer diagnoses it
A vetted, US-based systems engineer claims your ticket, usually within minutes during business hours, and investigates over a secure remote session you can watch and end at any time.
Fixed and verified with you
The engineer resolves the root cause and confirms with you that it’s working. You don’t just get a workaround, and you get a plain-English summary of what was wrong.
Pay only when it’s resolved
Fixed price from $99, invoiced only after you approve the fix. If it isn’t resolved, you don’t pay.
Frequently asked questions
Why does some mail work and some doesn't?
Exchange spreads outbound mail across the servers and routes it believes are available. If one of those is a retired server, only the share of messages sent that way gets stuck.
Will the stuck messages still go out?
Messages still in the queue can usually be delivered once routing is corrected. Anything that has already expired and bounced will need to be resent, and we help you identify which ones.