If you have quoted replies enabled, then the attribution line will appear above the quoted reply.
It normally looks something like this:
On Thu, 10 Sep 2019 3:15, Joe Bloggs wrote:
To customize the attribution line, go to the Settings → Preferences screen and click Show Advanced Preferences. In the "Writing" section, scroll to "Reply Attribution" and enter your desired text. You can use literal text, or you can use a pattern.
If you would like to use a pattern in your reply attribution, you can use the control characters below.
Sender details
%+f— the sender's name and email address.%+n— the sender's name (or email address, if no name is included).%+a— the sender's email address.
Message time
%d— the day of the month when the message was sent in mm-dd format (01-31).%e— the day of the month when the message was sent in dd-mm format (31-01).%m— the month when the message was sent in mm-yy format (01-12).%Y— the year when the message was sent (4 digits).%y— the year when the message was sent (last 2 digits).%H— the hour when the message was sent (00-23).%I— the hour when the message was sent (01-12).%k— the hour when the message was sent (00-23).%l— the hour when the message was sent (1-12).%p— "AM" or "PM" when the message was sent. This will be localized to your language where possible.%M— the minutes when the message was sent (00-59).%S— the seconds when the message was sent (00-59).%A— the weekday when the message was sent (Monday-Sunday).%a— the abbreviated weekday when the message was sent (Mon-Sun).%B— the month when the message was sent (January-December).%b— the abbreviated month when the message was sent (Jan-Dec).%z— the time zone offset for when the message was sent.
Some formats like %e, %k, %l are always 2 characters wide, and include a leading space. This is designed to make it simpler to format strings. If you would like to remove this space, place a - between the % and the letter, for example: %-e, %-k, %-l.
%eon the 6th day of the month produces6%-eon the 6th day of the month produces6.
Other control characters
%n— a new line.%%— the percent sign.