1.7 MB??? That's a big web image in any context, let alone in an email (where it's likely only downloaded once, so caching is of no use).
There's no absolute max single file size, since as you can see the GIF still loads, it just is a bad user experience.
I'd strive to keep individual images under 100K, the total of all images under 500K. But it's flexible: if you only have only image, maybe that one could be 200K.
You can use your browser to get a rough idea of end-user download times. On Chrome, it's Developer Tools » Network tab » Throttling dropdown. On a quality 4G link, a 1.7 MB img takes ~4s to download, and you feel it for sure.
Your .gif image size doesn't matter as you can use any size, but going with perspective of best practices, its not at all correct to use 1.7 mb file.
1) many email servers may spam your IP address as usually such large content is not part of good emails.
2) also many Email servers or ISP's in countries of Asia-pacific may also reject your email due to its large size.
3) The emails should be brief and quick that grabs the users interest and such emails may take a lot of time in loading all its contents which may make you loose your leads due to their loss of interest.
also many Email servers or ISP's... may also reject your email due to its large size.
This isn't really correct. Image tags that refer to remote (non-embedded) images do not contribute to email size detection at connection time. Looking only at the markup of an email doesn't tell you the bytes on the wire if images are enabled.
Thanks for correcting me here, but what I meant was.
Many office servers and Domains restrict the size of email( Body+content +Attachments) to be received. That is what i meant above and if you are planning to create an email that would not be fully viewed/ read by the lead, then you are loosing an opportunity.
That's still incorrect. Remote image filesize is not included in the "body + content + attachments" size calculated by real-world mail scanners. The principal worry is not that an email with a large binary image would not be received, it's that may not be viewed due to user impatience.