I want to display an alert when the size of an attachment exceeds 18MB.

[hkriwk1]

When you create an email from the case form, you can compose it in a new tab.
I want to implement a mechanism where, if you attach a file in that tab and its size exceeds 18MB, a popup appears.
How can these be achieved?

[Bhimashankar H]

Hi @hkriwk1 ,

By attachment property you can limit the attachment size. Add a Client Script tied to the email compose UI or use UI Script + onAttach/attachment events to detect newly added attachments and sum their sizes, then show a modal/alert if the total crosses get the value from system property.

For more detail

Please refer the below KB Articles

Email body/attachment size limit system properties 

Allowable size to a record 

This is Attachment limit properties &

Limit the maximum number of attachment in email 

Thanks,
Bhimashankar H

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If my response points you in the right directions, please consider marking it as 'Helpful' & 'Correct'. Thanks!

[Bhimashankar H]

Hi @hkriwk1 ,

I hope you saw my reply. 

If my response points you in the right directions, please consider marking it as 'Helpful' & 'Correct'. It will help future readers as well having similar kind of questions and close the thread.

Thanks,
Bhimashankar H