Maybe sending mail from PHP adds some kind of a field to the message header that identifies it as having been sent by a robot?
22.
In Outlook Express, if there is no Bcc field in the message header, go to the View menu and click on the All Headers option.
23.
Crandall says any special requirements placed upon spam, such as an advertising warning in the message header, should also be applied to radio and TV ads.
24.
UNH + 1 + PAORES : 93 : 1 : IA'- This is the message header segment which is required at the start of every message.
25.
:The date & time shown in an email are stored in the message headers, as are other details like the subject line and the sender's address.
26.
The header is split into the " Basic Header " ( shown as detached from the rest, in the diagram ) and " Chunk Message Header ".
27.
The Chunk Message Header contains meta-data information such as the message size ( measured in bytes ), the " Timestamp Delta " and " Message Type ".
28.
The Sweepstakes required a more complicated exchange of information for each two-way contact that was adapted from the message header structure used by the National Traffic System.
29.
The requester SHOULD not make any assumption about the usage of message header fields by the responding service, in particular the usage of fields like Subject, Message-ID or References.
30.
Lilly spokesman Jeff Newton said a message sent June 27 announcing the end of the service mistakenly included the e-mail addresses of all the subscribers in the message header.
