See RFC 2822, section 2.1.1 to start. There are two limits that this standard places on the number of characters in a line. Each line of characters MUST be no more than 998 characters, and SHOULD be no more than 78 characters, excluding the CRLF. As the RFC states later, you can work around this … Read more
SMTP protocol: smtps (port 465) v. msa (port 587) Ports 465 and 587 are intended for email client to email server communication – sending out email using SMTP protocol. Port 465 is for smtps SSL encryption is started automatically before any SMTP level communication. Port 587 is for msa It is almost like standard SMTP … Read more
From RFC 5321, section 2.3.11: The standard mailbox naming convention is defined to be “local-part@domain”; contemporary usage permits a much broader set of applications than simple “user names”. Consequently, and due to a long history of problems when intermediate hosts have attempted to optimize transport by modifying them, the local-part MUST be interpreted and assigned … Read more
Use email authentication methods, such as SPF, and DKIM to prove that your emails and your domain name belong together, and to prevent spoofing of your domain name. The SPF website includes a wizard to generate the DNS information for your site. Check your reverse DNS to make sure the IP address of your mail … Read more