Email uses a protocol called SMTP, it was invented an eon ago. It is insecure, lazy, slow and unreliable. That’s why we have so much spam. Then someone invented spam filtering. So the flow goes something like this :
WordPress website -> Local SMTP server -> Remote SMTP server -> Spam Filtering (black lists) -> Your Inbox
Some of the steps may or may not have authentication (passwords).
The black list is a reputation system for bad senders. It will include everyone that uses your hosting company – everyone that shares SMTP servers or IP addresses. If someone else starts to send spam, then the email you send with have a similar poor reputation and get you on the black list. This can easily change over time, without you touching anything on your site. Suddenly 1 day the emails silently coming to you.
There is a lot of steps that can go wrong, and they are hard to diagnose and fix.
I know a lot of people use email for leads/contacts etc. But it just clutters your inbox, leads can get lost or forgotten. What if the sales guy leaves , and he has all the leads in his inbox ?
How will you know if an email fails to get to you ? How are you going to follow up leads reliably ?
my 2c, email is a terrible solution for sending leads, and contact requests.
I implore you, don’t try to fix this broken solution. Just avoid it completely, and stop using email.
It is WAY WAY better to store the leads properly in a list – either inside WordPress, on an external list, or in a CRM. It avoids the whole drama of smtp, bounces, spam buckets. It also avoids stuff getting lost in your inbox.
Your leads are like gold. It’s difficult to get folks to your site. Perhaps its paid, perhaps it’s long hours of maintaining blog posts. And it’s even harder to get the lead. Eventually someone sends a lead, a request for contact. Them there’s your gold. Please store your gold safely in a vault somewhere.
mailchimp is free, and is a reasonable solution. But this isn’t meant to be a CRM discussion. Just don’t use email, please.
There are a bunch of plugins that remove the need for SMTP, but still send email, check this out:
https://wordpress.org/plugins/tags/wp_mail . Mandrill is popular, but its a paid option. There are particular gmail plugins also.