HTML reports instead of text for mail

Author: jfy133

main.nf

@@ -2926,11 +2926,11 @@ workflow.onComplete {
             log.info "[nf-core/eager] Sent summary e-mail to $email_address (sendmail)"
         } catch (all) {
             // Catch failures and try with plaintext
-              def mail_cmd = [ 'mail', '-s', subject, '--content-type=text', email_address ]
+              def mail_cmd = [ 'mail', '-s', subject, '--content-type=text/html', email_address ]
               if ( mqc_report.size() <= params.max_multiqc_email_size.toBytes() ) {
                 mail_cmd += [ '-A', mqc_report ]
             }
-            mail_cmd.execute() << email_txt 
+            mail_cmd.execute() << email_html 
             log.info "[nf-core/eager] Sent summary e-mail to $email_address (mail)"
         }
     }