If you are experiencing deliverability issues, don't just assume that your email vendor is too blame. First of all make sure you've done everything you should on your end to get the mail through.

Apart from the fact that you should only be mailing people that a) have signed up to receive your messages and b) are interested in what you have to say to them and c) you're doing this at a non-annoying frequency, Anne Holland from  MarketingSherpa suggest you double-check these three factors:

1. Are you currently using a dedicated IP address to send email that no other mailer ever uses? If not, you're at the mercy of every other mailer sending from the same IP address. If any of the folks on their list block or blacklist them, your mailings are tarred with the same brush because you appear to be identical.

2. If you send in HTML, is it coded properly? To see if your HTML passes the test, run it through the w3.org online validator.

3. Content filtering is *huge* in the corporate world. If your copy contains enough junk-mail-looking words, your mailing to folks at work may not get through. To see if your copy passes the test, run it through the Lyris online validator (or ask if your ESP provides a similar checker).

Read the full article here.