Here is a dynamic way to do it. This will count up mail servers and add them to the drop down box. If you 2 server it will show those two, if you have 100, it shows 100 servers.
<input type="time" token="global_time" searchWhenChanged="true">
<label>Time frame</label>
<default>Last 24 hours</default>
</input>
<input type="dropdown" token="Mailserver" searchWhenChanged="true">
<label>Mailserver</label>
<search>
<query>sourcetype=api "analyzed email count"
| rex "xxx (?<server>\S+)" # Here you need to make a rex to extract name of your mail server
| top limit=0 server
<earliest>$global_time.earliest$</earliest>
<latest>$global_time.latest$</latest>
</search>
<choice value="*">Any</choice>
<fieldForLabel>server</fieldForLabel>
<fieldForValue>server</fieldForValue>
<default>*</default>
</input>
Then in you panel you add the following search:
sourcetype=api "analyzed email count" $Mailserver$ | stats sum(mail_value) AS "Total"
If you post some lines that show how mail server looks like, I can make the regex to extract it for you.
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