Here's the documentation for the send mail script step:
Tie it to your button, then in the script settings for the "To" field, select the email field.
Also set it to use the mail client, not SMTP; check "current record" and not "found set", and uncheck "perform without dialog".
This will open a new email message using the user's default email client, with the specified record's email address in the to field.
You can specify other options as well.
I too have been going through this process ... and through trial and error ... here is what has worked and not worked for me. First ... the not worked....
Send Mail using SMTP ... was able to create send the email, but it would always go to junk email of receive. Based on reading, this is because Filemaker does not create a proper email header or something.
Send Mail using Client ... would not work for me. We use 64 bit Filemaker along with a 64 bit Troi File plugin (used to automatically bring up mechanical drawing records), but all of our email clients are Outlook 32 bit. 64 bit Filemaker does not work nicely with 32 bit Outlook clients.
So, I decided to use Send Event and call the mail client directly.
# Below creates unique name for creating a PDF in users TEMP directory
Set Variable [ $PDFPath; Value: Get (TemporaryPath) & Get (UUID) & ".PDF"]
# Now create the PDF
Save Records as PDF [Restore; No Dialog; "$PDFPath"; Records being browsed]
# Now create some temporary variables for mail command
Set Variable [$MailToLine; Value: "/m \"" & PO::Email & "&subject=PO: " & PO::PONo & "\""]
Set Variable [$AttachmentLine; Value: "/a \"" & Right ($PDFPath; Length ($PDFPath) - 1) & "\""]
# Now create the entire Mail Command
Set Variable [$MailCommand; Value: "outlook.exe /c ipm.note " & $MailToLine & " " & $AttachmentLine]
# Finally - use Send Event and pass it the mail command
Send Event ["aevt"; "odoc"; $MailCommand]
Note - in order to get this to work - I have to set the PATH environmental variable on each client.
To the PATH variable, I have to add the directory location of the Outlook.exe executable.
Each client machine uses Outlook, although we have many different versions of Outlook in use (2007/2010/2016).
This has worked for me ... it brings up the email client, populates the To:, the Subject: and attaches the PDF.
In this case, Open URL with a mailto: URL format can also open a mail program. Just some food for thought.
I forgot to mention, but yes, I tried that option as well. The mailto: URL does not allow for attachments.