The following are reserved and cannot be used as custom field names. If you need to use a similar name, you can change it slightly (e.g. accName is reserved, acc-Name is not).
| accName |
| addressFromName |
| alternativeSignupdate |
| customDomain |
| deviceBrowser |
| deviceOs |
| deviceType |
| email_hash |
| emailEnc |
| errorUrl |
| languageCode |
| lastClicked |
| lastOpened |
| listName |
| mailVariationid |
| messageName |
| mobile |
| optinUrl |
| subject |
| successUrl |