Some things still wonder me, after 10+ years of web-development. Todays wonder is here:
RFC2821 (SMTP) tells: The maximum total length of a text line including the
Actually, there is even a PHP-bug reported, regarding this, but PHP obviously can’t do anything to help the situation
The solution is really simple: if there is a chance, that lines of your emails would be longer than 990 bytes encode body using base-64. The easiest way to do it for emails without attachments, in php is to use mb_send_mail() function instead of mail(), as it will apply encoding automatically.