Could anyone please tell me what would be the best way to guarantee the maximum uptime on a email solution. Maybe puting the NS1 and NS2 on different hosting companies, or if there is a hosting company specialized in relieble email service?

Thx in advance for your help.

Hey,
You could add multiple email recieving servers.. this can be done by adding more MX records in your DNS.

kunal

setup 5 backup MX servers..

1 in each part of the USA :)

etreus,

What do you mean by reliability? it can have different dimensions

What I am saying is my opinion and arguable.

If you are looking at emails addressed to you not getting lost, multiple MX records may neither be necessary nor sufficient; what you need is multiple, remotely located DNS servers so that your MX records have 100% availability.
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they are not necessary because:

Almost all SMTP servers [to my knowledge] will attempt to cache mails to a domain for a period of 24-48-72 hours and if your server can get up from a downtime within that period you would still receive all mails

they are not sufficient because:

With 5 MX records with increasing order of preference , if your DNS server is down your mails will still be bounced back
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If you are looking at timely [near instant] receipt of mails then multiple MX records are in order.

SMTP is less of a problem since if your domain mail server is down you can always use your ISP's SMTP [if your ISP is down , you cant anyway use the internet]

If you want reliability in terms of no one reading your mail then APOP kind of authentication is recommended

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As I said these are my opinions and may be wrong too! After all I am just a Fool :)

Cheers
Balaji