emails sent 2 mins apart arrive 1 hour apart

[Tony]

My sister in UK sent me an email. 2 mins later she sent another one. The second one arrived first, 1 hour before the first one! This is not the first time this has happened. Any email transmission experts know what's going on?

[Paul.Cov]

I know nothing about the deeper workings, but I believe if for any reason an email transmission fails, then it essentially gets put aside to retry transmission some time later.
If they set this wait time too short, then their own systems risk being overwhelmed by retry attempts in the event of a big outage. If they set the wait time too long, then recipients like yourself can experience these long delays, or messages out of sync with the order they were sent.

[wainuitech]

Could write out a lot of how they work, BUT simple solution. Watch a Video Called Warriors of the net. Its an old video that explains in a comic sort of way how the internet ( including email) Actually works.

While its old, it uses a netscape browser it describes exactly what happens, some may laugh but doesn't matter how complicated things get this is STILL the basics of it. It will expalin why your mail does what it did Its more about what happens when you clcik on a link but doers hit on email as well. While its based on business it still applies to every day.

Here you go https://www.youtube.com/watch?v=PBWhzz_Gn10

[fred_fish]

The headers of each message will have timestamps for each hop on the delivery, so you can see which server was the holdup.

[Tony]

The headers of each message will have timestamps for each hop on the delivery, so you can see which server was the holdup.

I had actually done that and I can see the point at which the timestamps separate, but I can't interpret the rest of it to see what is happening at that point, or why.

[fred_fish]

Without access to the logs of those servers (or maybe any public reports) you can only guess what the temporary error could be.
Most likely just congestion, or maybe a temporary DNS error or possibly a swiftly rectified blacklisting.

[Tony]

Yes, I suspect it will always be a mystery. My interest was piqued because it is at least the second time it has happened. My sister has a tendency to send me something then almost immediately send a follow-up. Probably not relevant but in each case the first email (which arrived second) contained some photos as attchments.

[1101]

Greylisting
or other spam filter weirdness.

Or , the 1st failed/bllocked , so the email server waited an hour & retried

[paulw]

Email is not guaranteed to be an instant service.

[wainuitech]

All the posts explaining are 100% correct, the Video I linked explains it all really in simple terms.

MANY people don't know how emails or the internet actually works (or doesn't).

Many people think that when you send an email it goes in one piece like if you posted a letter in a envelope -- NOPE, doesn't work that way. When you actually understand how it all works then it makes perfect sense as to why there are delays.