12 C.F.R. § 1006.6
(a) Definition. For purposes of this section, the term consumer includes:
(b) Communications with a consumer—(1) Prohibitions regarding unusual or inconvenient times or places. Except as provided in paragraph (b)(4) of this section, a debt collector must not communicate or attempt to communicate with a consumer in connection with the collection of any debt:
(2) Prohibitions regarding consumer represented by an attorney. Except as provided in paragraph (b)(4) of this section, a debt collector must not communicate or attempt to communicate with a consumer in connection with the collection of any debt if the debt collector knows the consumer is represented by an attorney with respect to such debt and knows, or can readily ascertain, the attorney's name and address, unless the attorney:
(4) Exceptions. The prohibitions in paragraphs (b)(1) through (3) of this section do not apply when a debt collector communicates or attempts to communicate with a consumer in connection with the collection of any debt with:
(2) Exceptions. The prohibition in paragraph (c)(1) of this section does not apply when a debt collector communicates or attempts to communicate further with a consumer with respect to such debt:
(2) Exceptions. The prohibition in paragraph (d)(1) of this section does not apply when a debt collector communicates, in connection with the collection of any debt, with a person:
(3) Reasonable procedures for email and text message communications. A debt collector maintains procedures that are reasonably adapted, for purposes of FDCPA section 813(c), to avoid a bona fide error in sending an email or text message communication that would result in a violation of paragraph (d)(1) of this section if those procedures include steps to reasonably confirm and document that:
(4) Procedures for email addresses. For purposes of paragraph (d)(3)(i) of this section, a debt collector may send an email to an email address if:
(i) Procedures based on communication between the consumer and the debt collector.
(ii) Procedures based on communication by the creditor.
(C) Before the debt collector used the email address to communicate with the consumer about the debt, the creditor sent the consumer a written or electronic notice, to an address the creditor obtained from the consumer and used to communicate with the consumer about the account, that clearly and conspicuously disclosed:
(1) That the debt has been or will be transferred to the debt collector;
(2) The email address and the fact that the debt collector might use the email address to communicate with the consumer about the debt;
(3) That, if others have access to the email address, then it is possible they may see the emails;
(4) Instructions for a reasonable and simple method by which the consumer could opt out of such communications; and
(5) The date by which the debt collector or the creditor must receive the consumer's request to opt out, which must be at least 35 days after the date the notice is sent;
(iii) Procedures based on communication by the prior debt collector.
(5) Procedures for telephone numbers for text messages. For purposes of paragraph (d)(3)(i) of this section, a debt collector may send a text message to a telephone number if:
(i) The consumer used the telephone number to communicate with the debt collector about the debt by text message, the consumer has not since opted out of text message communications to that telephone number, and within the past 60 days either:
(ii) The debt collector received directly from the consumer prior consent to use the telephone number to communicate with the consumer about the debt by text message, the consumer has not since withdrawn that consent, and within the past 60 days the debt collector either: