Alexander Shukaev <haroogan@gmail.com> writes:

> On Mon, Jun 29, 2015 at 10:26 PM, Alexander Shukaev <haroogan@gmail.com>
> wrote:
>
>> Alright, so as soon as I added
>>
>> (setq gnus-select-method '(nnimap "imap.gmail.com"
>>                                   (nnimap-server-port 993)))
>>
>> Notice the explicit port 993 (i.e. "imap", "imaps", etc. don't work).
>> Probably on Windows, one has to add
>>
>> imaps 993/tcp # IMAP over SSL
>> imaps 993/udp
>>
>> to 'c:/WINDOWS/system32/drivers/etc/services'?
>>
>> Anyway, now I'm getting
>>
>> Opening connection to imap.gmail.com via tls...
>> nnimap (imap.gmail.com) open error: 'NO (ALERT) Please log in via your
>> web browser: https://support.google.com/mail/accounts/answer/78754
>> (Failure)'.  Continue? (y or n) n
>>
>> What is that supposed to mean?  A problem with credentials?
>>
>> Kind regards,
>> Alexander
>>
>
> ​P.S.: I also got an e-mail from Google:
>
> ​
>> Hi Alexander,
>
>
>> We recently blocked a sign-in attempt to your Google Account [
>> ​*
>> @gmail.com].
>
>
> ​Huh?​

As mentioned by Jorge, if you have two step authentication enabled in
googl;e, you need an appilt=cation password to use imap. Some info can
be found at [1].

Concerning the blocking: I guess google blocked this attempt, because
you tried to often in a time? Otherwise there are more hints in the
email.

I am by the way using offlineimap to sync my gmail to a local dovecot
imap server which I access from gnus. Works perfectly.

Cheers,

Rainer

Footnotes: 
[1]  https://support.google.com/mail/answer/1173270?hl=en

-- 
Rainer M. Krug
email: Rainer<at>krugs<dot>de
PGP: 0x0F52F982