Make explicit you define variables for all recipients
Revert indentation changes from #68
Cast recipient variables to a string
Relocate MailgunMessage instance check
Simplify check on instanceof MailgunMessage
Extract getRecipientVariables() into variable
s/$recipientEmail/$recipient
Throw an SlmMail Runtime exception
Extract variables outside if() statements
Merge pull request #69 from juriansluiman/hotfix/mailgun-bulk-adjustments

Hotfix/mailgun bulk adjustments