My homestead/roundcube email account rejecting gmail email accounts and I keep getting a security certificate error when using Outlook

I have been using Outlook 365 for a long time now for email and routing my homestead email through it. As of about 6 months ago, I started getting a security certificate error everytime I opened outlook and every time I try to send an email with my roundcube homestead email account erik@t-shirtmadness.com. First with gmail email accounts, I keep getting a permanent error and rejection email for the last 3 weeks. I says the following address failed. Permanent Error due to authentication. Here is the verbiage:

host gmail-smtp-in.l.google.com [172.253.63.26]

    SMTP error from remote mail server after end of data:

    550-5.7.26 This message does not pass authentication checks (SPF and DKIM both

    550-5.7.26 do not pass). SPF check for [t-shirtmadness.com] does not pass with

    550-5.7.26 ip: [66.96.184.6].To best protect our users from spam, the message

    550-5.7.26 has been blocked. Please visit

    550-5.7.26  https://support.google.com/mail/answer/81126#authentication for more

    550 5.7.26 information. f5-20020ac87f05000000b003b3c56ce5b2si2800606qtk.367 - gsmtp

And then everytime I send an email for the last year, I get a security certificate error. Here is that error: It says the server you are connected to is using a security certificate that cannot be verified. The target principal name is incorrect. This is a pop up box that happens everytime I open up the email and when I send an email. I can click on the repair function in account settings and it fixes, but I'm not sure why. When I go into the advanced settings of Outlook. All settings are the same as before repaired Need help. Erik Mellenberg