I'm noticing that e-mails sent from my device are being tagged as "undisclosed recipients" as the sender wather than my e-mail addy. People are getting my e-mails and questioning the e-mail addy. What do I have to reset?

If all (or some) of your addressees are BCC (blind carbon copy) there will be no TO header and email applications will use the undisclosed recipients phrase.

BTW this is proper email etiquette if all recipients should get the message, but don't need to know each others' email addresses. Mailing lists are a good example of this.