Changing domain name host - Page 2

BritTim · 13 Feb 2025, 05:03 AM

Quote:

Originally Posted by TenFour

Right, but let's say you are moving from one email service to Fastmail. At the current email service you have manually entered DNS for that service, but when you switch to FM you want to use their Nameservers and let them do all the DNS setup. What happens to your email in that case?

Changing the server(s) used for email is trickier. The Fastmail help pages provide some guidance on this. You should not change Nameservers and mail servers at the same time. In a business setting,, in fact, the DNS changes are far from the biggest challenge. In most cases, old email messages will need to be transferred between the old and new servers, and setting changes on the mail clients will be necessary. This tends to be a pretty complex project that needs careful planning.

TenFour · 16 Feb 2025, 12:49 AM

Quote:

Changing the server(s) used for email is trickier. The Fastmail help pages provide some guidance on this. You should not change Nameservers and mail servers at the same time. In a business setting,, in fact, the DNS changes are far from the biggest challenge. In most cases, old email messages will need to be transferred between the old and new servers, and setting changes on the mail clients will be necessary. This tends to be a pretty complex project that needs careful planning.

I'm thinking of it from a consumer perspective. Fastmail has its own email migration tool. What I'm wondering is what happens to emails sent to you during the period when you have just signed up for Fastmail, switched to the FM nameservers, and are awaiting the progation of that info. around the Internet. I suspect some people will get a bounce message or am I wrong and will email systems retry for a day or so before sending back a message that the email is undeliverable?

BritTim · 16 Feb 2025, 04:03 AM

Quote:

Originally Posted by TenFour

I'm thinking of it from a consumer perspective. Fastmail has its own email migration tool. What I'm wondering is what happens to emails sent to you during the period when you have just signed up for Fastmail, switched to the FM nameservers, and are awaiting the progation of that info. around the Internet. I suspect some people will get a bounce message or am I wrong and will email systems retry for a day or so before sending back a message that the email is undeliverable?

Maybe, I am misunderstanding you, but it seems that you are talking about switching email to a new service. What happens to messages delivered just after the DNS is changed is that messages will be randomly delivered to the old or new service for a period equal to the TTL of the DNS entries. Assuming you have correctly set the TTL to about five minutes, this means that a a message sent within this five minute period might arrive at the old mail server. In practice, this is not a major problem. Maybe, 10 minutes after the DNS change, you go to the old server and check if there are messages that still need to be transferred to the new service (in our case, Fastmail). In practice, messages from an hour or two prior to the DNS change will probably also need to be transferred to join messages transferred earlier.

TenFour · 16 Feb 2025, 05:39 AM

Quote:

Maybe, I am misunderstanding you, but it seems that you are talking about switching email to a new service. What happens to messages delivered just after the DNS is changed is that messages will be randomly delivered to the old or new service for a period equal to the TTL of the DNS entries. Assuming you have correctly set the TTL to about five minutes, this means that a a message sent within this five minute period might arrive at the old mail server. In practice, this is not a major problem. Maybe, 10 minutes after the DNS change, you go to the old server and check if there are messages that still need to be transferred to the new service (in our case, Fastmail). In practice, messages from an hour or two prior to the DNS change will probably also need to be transferred to join messages transferred earlier.

Thanks! Makes sense.

n5bb · 16 Feb 2025, 08:03 AM

Yes - if you want to get the fastest and most seamless switchover to your new DNS settings (such as the MX mailserver), you need to do the following:

First, be sure to examine the TTL (Time To Live) on all of your old existing DNS entries. Copy these so you know how long your old DNS entries will remain cached.
Then set the TTL on the old DNS entries (such as MX) to a very small value, such as 10 seconds to 5 minutes.
Now you come to the aggravating part of the process. You need to wait a bit longer than the old TTL time you noted in the first step before you can assume that caches will use the new short TTL time, ensuring that services (such as a sending email server) will quickly update based on the authoratative DNS information.
After waiting a bit longer than the old TTL interval, you can now change your DNS entries to the new values, including new TTL values. It?s recommended to not use a very small TTL value for normal use, since it places some stress on the system and could slow down DNS queries, since you would be essentially turning off DNS caching. One day (86400 seconds) is a commonly used value.
TTL (Time To Live) controls caching throughout the internet. If it?s set too short (such as 10 seconds), then nearly all emails you receive to your domain will be slowed down by an authoritative DNS request, since you have essentially disabled caching, and the DNS system will be loaded with a lot of extra requests. If it?s set too long (such as a week), you won?t be able to guarantee that the old DNS data is flushed out of the network caches in a timely fashion when you need to change your DNS entries. So it?s a compromise.
This is how it?s supposed to work. But it seems that some network equipment may have TTL settings which ignore the TTL set in your DNS entries, and other systems may take a bit longer than the actual TTL value. So that?s why I said ?a bit longer?.
As pointed out earlier on this thread, if you change your DNS entries without the process I listed above, then some systems may get the new DNS values quickly (because their cache has timed out) and others may take much longer (if they just resolved your old entry with a long TTL and then cache it for a day or more). So that could result in emails from various senders arriving seemingly randomly at your old and new email provider. It?s not really random - it all depends on the status of their caching of your DNS entries. So that?s why I suggest the multistep TTL change with the added delay before the actual MX change, so you have a high probability that it will switch over cleanly.

Bill

nighthawk700 · 16 Feb 2025, 11:26 PM

Thanks everyone, for your comments. Since I have a lot going on now, and my daughter is using the domain address in her job search etc., I renewed on GoDaddy for 5 years. I set myself a calendar alert for 4.5 years from now, with a link to this forum/topic so I can do my research and maybe reach out to the Fastmail team as well, if needed, and work out the best way to get my domain name moved to a new platform (spaceship, porkbuns, or similar) and point that one to Fastmail without losing access.

16 Feb 2025, 08:03 AM	#20
n5bb Intergalactic Postmaster Join Date: May 2004 Location: Irving, Texas Posts: 9,031	Yes - if you want to get the fastest and most seamless switchover to your new DNS settings (such as the MX mailserver), you need to do the following: First, be sure to examine the TTL (Time To Live) on all of your old existing DNS entries. Copy these so you know how long your old DNS entries will remain cached. Then set the TTL on the old DNS entries (such as MX) to a very small value, such as 10 seconds to 5 minutes. Now you come to the aggravating part of the process. You need to wait a bit longer than the old TTL time you noted in the first step before you can assume that caches will use the new short TTL time, ensuring that services (such as a sending email server) will quickly update based on the authoratative DNS information. After waiting a bit longer than the old TTL interval, you can now change your DNS entries to the new values, including new TTL values. It?s recommended to not use a very small TTL value for normal use, since it places some stress on the system and could slow down DNS queries, since you would be essentially turning off DNS caching. One day (86400 seconds) is a commonly used value. TTL (Time To Live) controls caching throughout the internet. If it?s set too short (such as 10 seconds), then nearly all emails you receive to your domain will be slowed down by an authoritative DNS request, since you have essentially disabled caching, and the DNS system will be loaded with a lot of extra requests. If it?s set too long (such as a week), you won?t be able to guarantee that the old DNS data is flushed out of the network caches in a timely fashion when you need to change your DNS entries. So it?s a compromise. This is how it?s supposed to work. But it seems that some network equipment may have TTL settings which ignore the TTL set in your DNS entries, and other systems may take a bit longer than the actual TTL value. So that?s why I said ?a bit longer?. As pointed out earlier on this thread, if you change your DNS entries without the process I listed above, then some systems may get the new DNS values quickly (because their cache has timed out) and others may take much longer (if they just resolved your old entry with a long TTL and then cache it for a day or more). So that could result in emails from various senders arriving seemingly randomly at your old and new email provider. It?s not really random - it all depends on the status of their caching of your DNS entries. So that?s why I suggest the multistep TTL change with the added delay before the actual MX change, so you have a high probability that it will switch over cleanly. Bill

16 Feb 2025, 11:26 PM	#21
nighthawk700 Essential Contributor Join Date: Oct 2004 Location: Baltimore, MD Suburbs (US) Posts: 242	Thanks everyone, for your comments. Since I have a lot going on now, and my daughter is using the domain address in her job search etc., I renewed on GoDaddy for 5 years. I set myself a calendar alert for 4.5 years from now, with a link to this forum/topic so I can do my research and maybe reach out to the Fastmail team as well, if needed, and work out the best way to get my domain name moved to a new platform (spaceship, porkbuns, or similar) and point that one to Fastmail without losing access.