Bem, acho que esta é a política de spam da GoDaddy implementada. Existem algumas pessoas com o mesmo problema:
In 2003, the Can't Spam Act was implemented. Since then, large email hosting companies like GoDaddy have had to constantly balance the filters on their servers. If a certain email account gets flagged as spam, sometimes the entire server gets shut down until GoDaddy can either adjust the filters or weed out the problem customer who is spamming. This causes a lot of other emailers whose emails go through that same server to have an interruption in their service. Therefore, Godaddy (and other email hosting companies) are constantly walking a fine line. If they make the email filters too strict, the server overreacts and treats our harmless emails as spam or a virus. If they make the filters too loose, then the whole server may be shut down because of a spammer. When I asked why it goes through if I try to resend the email, he said it's because different servers have different filters and he reminded me that it is a constant balance they will always be working on....
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algumas pessoas mudaram o Godaddy para outro hoster para corrigir esse problema.