Direct Send - Bypass your SMTP Server
Standard method of sending email is through
the outgoing SMTP server. Some of the bulk email software
such as AY Mail, offer alternative
method - bypassing the SMTP server and sending directly
to the destination (see our article about
Here we summarize pros and cons of these methods.
Cannot be used when your Internet Service Provider
blocks port 25 connections, or MX record lookup is unavailable.
This is a typical situation for corporate users located
behind a corporate firewall.
Some of the ISP may redirect all the connections to their
own SMTP server regardless of what SMTP server you're trying
to contact. You may think you're sending direct, but in
fact you're using their server.
Requires SMTP server. Cannot be used if the SMTP
server has severe limitations or causes severe delays.
Not very reliable. When you send bulk email,
the mail program has to connect to many different servers. Some of
these servers may be down, connections may break. The bulk email
software cannot deal with these problems in a reliable way.
You may need to re-send to the temporarily failed recipients
several times over to make sure that all the addresses are covered.
Reliable. Once the mail is transmitted to the
SMTP server, the server takes care of the sending. If some of
the servers are inaccessible, or when connections break, the
server may just queue the message for the future. Being constantly
connected to the Internet, server can keep trying for several
days until email is sent.
You cannot send
which may make sending to very large lists prohibitively
You can send
non-personalized messages, which
results in very fast sending. See bulk
email speed test.
Because you are dealing with multiple
servers, you can use multithreading, that is multiple
parallel connections. If you have a fast Internet connection,
this may speed things up.
It may not be practical to use multithreaded
connections to the same server.
Your recipients receive your messages as you send.
The SMTP has to send out the messages after
you transmit them. The server may delay mail delivery if it feels busy.
If the address is undeliverable, your bulk
email software will know immediately. Therefore, direct send
reduces the number of bounces you receive.
You will receive bounces for all the
Some of the destination servers would
block your mail because they know that your computer is
not a regular SMTP server.
See our article about bulk email
Your mail will be sent out from a regular
SMTP server, so it is unlikely to be blocked at the
In most cases, we recommend traditional method.
It is up to you to decide which method is better in your
You may find advantageous to use a combined method -
You first send your mail using direct sending. Then you
classify all the failures into temporary (for example because
the destination server is down) or permanent (for example
non-existent mail account), and then re-send to the
temporarily failed recipients through your SMTP server.
AY Mail does the classification
automatically as it sends.
This will reduce the number of bounces, but still will
give you reliability of a regular SMTP server.